% texpower.sty,v 1.23 2003/05/15 12:33:08 hansfn Exp
%  
% TeXPower bundle - dynamic online presentations with LaTeX
% Copyright (C) 1999-2002 Stephan Lehmke
% 
% This program is free software; you can redistribute it and/or
% modify it under the terms of the GNU General Public License
% as published by the Free Software Foundation; either version 2
% of the License, or (at your option) any later version.
% 
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
%=======================================================================================================================
% File: texpower.sty
%
% LaTeX Package for creating `dynamic' presentations.
%
%
% DISCLAIMER: This is a PRE-ALPHA release of the texpower package, mainly for getting feedback on the
%             implementation. 
%
%             During the subsequent error correction and extension of the functionality, the syntax and implementation
%             of the macros are liable to change. 
%
%             So far, the texpower package itself contains only scarce inline documentation, as the code is too
%             much of a moving target to make rigorous documentation a sensible endeavour. As soon as the
%             texpower package is ready for beta release, it will be made into a fully documented dtx file.
%
%             The TeXPower Bundle can be found at
%             http://texpower.sourceforge.net/
%
%             Some documentation, examples and an FAQ list are
%             contained in the docs, available at
%             http://prdownloads.sourceforge.net/texpower/texpower-doc-pdf-0.0.8f.tar.gz
%             
%=======================================================================================================================
% Author: Stephan Lehmke <Stephan.Lehmke@cs.uni-dortmund.de>
%
% v0.0.1 Oct 26, 1999 First pre-alpha version.
% 
% v0.0.2 Feb 15, 2000 Squashing a bug...
% 
% v0.0.3 Mar 13, 2000 Tidying up command syntax; adding some in-line documentation.
% 
% v0.0.4 Mar 17, 2000 In-line documentation for the first pre-alpha version completed.
% 
% v0.0.5 Mar 17, 2000 Fixed some problems with incompatible versions of hyperref (spotted by Marc van Dongen).
%                     (Apr 14: this code no longer exists)
% 
% v0.0.6 Mar 20, 2000 Added papersize settings. (Mar 28: these are now in fixseminar.sty)
%
% v0.0.7 Apr 07, 2000 Removed dependency on hyperref; added support for color emphasis; respect the display option;
%                     now loading /etc/texpower/tpsettings.cfg and /etc/texpower/tpoptions.cfg; added \bstep, \switch, \rebstep, \reswitch.
%
% v0.0.7a Apr 28, 2000 \pause and \stepwise now use \leaders for inserting duplicated parts of pages. This way,
%                      processing of whatsits is turned off in the duplicates so that table of contents entries are no
%                      longer duplicated when a section occurs on a page where \pause or \stepwise is used (spotted by
%                      heiner richter). Thanks to Heiko Oberdiek for his suggestion how \leaders can be successfully
%                      applied for this purpose.
%                      \stepwise now does the right thing if no \step command occurs in <contents>.
%                      There was a bug in \save@TP which would become apparent if \stepwise was the first thing on a
%                      page. Spotted and fixed by Ross Moore (thanks!).
%
% v0.0.7b May 04, 2000 \@ifpackagelater{hyperref}{2000/03/22} changed to \@ifpackagelater{hyperref}{2000/03/23}. Spotted
%                      by Ross Moore. 
%
% v0.0.7c May 06, 2000 \eject changed to \newpage in \stepwise to cure some problems with the foils package. Spotted
%                      by Ross Moore. 
%
% v0.0.7d May 18, 2000 \everydisplay finally removed from colormath option because it only causes trouble. Maybe I
%                      should look for a less fragile solution for the whole thing. Fixed a bug in texpower's definition
%                      of \set@page@color (used only if pdftex.def doesn't define it) which would cause a fatal error if
%                      two \pagecolor commands occur. Added command \replacecolor.
%
% v0.0.8  May 24, 2000 Now providing two methods for creating duplicates of page contents (used by \pause and
%                      \stepwise). The former default method using \leaders, which leads to problems with footnotes
%                      (spotted by heiner richter), is now activated by the newly introduced option
%                      robustduplicates. The new default method uses \unvbox as the \pause command from texpause.sty,
%                      but redefines \write for suppressing duplicate toc and bookmark entries due to duplicated
%                      whatsits. 
%                      Changed the way \liststepwise and \parstepwise are implemented. Instead of wrapping the whole
%                      <contents> in a minipage (which caused a lot of problems), an invisible \hrule is inserted in
%                      front of <contents>, which seems to do the job as well. With option robustduplicates, this seems
%                      to be unneccessary for \parstepwise.
%                      Now all counters are saved before \stepwise starts and restored for every \step. This remedies
%                      problems with equation numbers etc.
%                      Added a modification for the slides class so that slides are not centered if the display option
%                      is given.
%                      Option slifonts now also handles math fonts.
%                      Added a \hidetext command which respects line breaks (needs soul package).
%
% v0.0.8a Jun 02, 2000 Fixed a bug in the code which disables \pageDuration if the pdfpageduration key doesn't exist
%                      (spotted by Friedrich Eisenbrand).
%
% v0.0.8b Jun 09, 2000 Added additional `dimmed' and `enhanced' color sets for all standard colors, with corresponding
%                      commands \dimcolors and \enhancecolors.
%                      Added a `color stack correction' option fixcolorstack, which should avoid that the duplication of
%                      ``color push'' and ``color pop'' specials confuses the driver's color stack
%                      (spotted by Ross Moore).
%                      Added new display commands \hidedimmed, \hidevanish, \highlightenhanced.
%                      Added \step variants \dstep and \vstep.
%                      Added patches for \[, equation, eqnarray, and eqnarray* when the colormath option is used.
%                      Now also saving and restoring footnotes at \pause and \stepwise.
%                      Added a command \releasecounter to keep a counter from `freezing' during the execution of
%                      \stepwise. 
%
% v0.0.8c Jun 13, 2000 The default duplication method will now (only) attack \protected@write. There's a new option
%                      hackwrite which restores the former default method (of attacking \write).
%                      Corrected a bug newly introduced into \switch with version 0.0.8b.
%                      Corrected a bug in the color correction code (spotted by Ross Moore).
%
% v0.0.8d Jun 15, 2000 Corrected a minor quirk in \hidetext.
%                      Added a command \addTPcolor for defining new `standard' colors.
%                      In printout versions, the last step will no longer think it's `first activated'.
%
% v0.0.8e Jun 21, 2000 Yet another rewrite of the page duplication code. I hope it's perfect this time :)
%                      The options robustduplicates and hackwrite are obsolete now.
%                      Thanks to Martin Schroeder for permission to use his everyshi code.
%                      Fixed a small quirk in \dstep and \vstep.
%                      \darkbackground and relatives now set both page and text color.
%
% v0.0.8f Jun 27, 2000 A small change in the definition of \liststepwise to enhance vertical spacing.
%
% v0.0.8g Jul 19, 2000 Color management extended and largely rewritten.
% NEVER RELEASED       A small change to make page transition and page duration settings local to groups.
%                      \dstep and \vstep now understand the usual optional arguments.
%
% v0.0.9  Oct 17, 2000 Added support for structured backgrounds (command \backgroundstyle).
% NEVER RELEASED       New commands for gradient rules and boxes.
%                      Added a hack to keep hyperref from producing duplicate page anchors (suggested by Thomas Emmel).
%                      Some slight changes in the mode of accounting in \step to hopefully give better results for
%                      `complicated' orders of activating steps using \step's optional arguments.
%                      Added (experimental) commands \multistep and \movie for aiding in (simple) animations.
%                      \pagecolor hack removed, as pdftex.def on CTAN now supports \pagecolor.
%                      \set@color hack for seminar removed (made unneccessary by enhancements to powersem).
%                      Added rudimentary support for panels.
%                      Added rudimentary support for navigation elements.
%                      Now put a hyper anchor ``firstpage.n'' on the first element of the sequence for page n.
%
% v0.0.9a Feb 01, 2002 Tidying up the inline documentation.
% NEVER RELEASED       When the color package is loaded before texpower, texpower's color management is no longer
%                      activated automatically.
%                      Definitions of standard colors moved to file /etc/texpower/tpcolors.cfg.
%                      Option `slifonts' is obsolete now. The code is now part of the much more sophisticated package
%                      ``tpslifonts''.
%                      Now the `colormath' option cooperates with array.sty (and thus colortbl.sty).
%                      New option ``nineminutes'' to circumvent a strange behaviour of acrobat/acroread v4.05 and later
%                      wrt. page duration.
%                      Option `fixcolorstack' now checks also for VTeX.
%                      \hidedimmed, \highlightenhanced and \dstep now check for math mode.
%                      Now using ifpdf package if available.
%
% v0.0.9b Nov 13, 2002 colormath adapted to different handling of `equation' by amsmath 2.x.
% NEVER RELEASED       Adapted for new version of soul package.
%                      Added another patch to colormath for handling array package's ``m'' columns without color change.
%                      `Turn on' seminar parameters in panel boxes even before \begin{document}.
%                      Added a command \overlays, sibling of \multistep, which prints all steps over each other.
%                      Added a command \steponce, sibling of \step, which is active only for one step.
%                      Removed a bug in color correction code introduced in v0.0.8g.
%
% v0.0.9c Apr 29, 2003 A small fix to give \overlays a width.
% NEVER RELEASED       \mklength is now a user command.
%                      The \@nobreak switch and \everypar are now saved and restored by \stepwise, hopefully enhancing
%                      cooperation with section headings and list environments.
%                      Changed \newcommand to \providecommand to allow background.sty to be loaded in parallel (thanks
%                      to Hans Fr. Nordhaug for the original patch).
% v0.0.9d May 15, 2003 RELEASED.


\NeedsTeXFormat{LaTeX2e}

\ProvidesPackage%
{texpower}%
[2003/05/15 v0.0.9d Create Dynamic Presentations with LaTeX.]


%=======================================================================================================================
% We need the programming tools provided by these packages.

\RequirePackage{ifthen}
\RequirePackage{calc}
\RequirePackage{keyval}


%=======================================================================================================================
% Options and general setup.

%-----------------------------------------------------------------------------------------------------------------------
% General options.

% The option verbose turns on some automatic messages.

\newboolean{verbose@TP}
\DeclareOption{verbose}{\setboolean{verbose@TP}{true}}


% The (global) option display is respected and turns on the `dynamic' features.

\provideboolean{display}
\DeclareOption{display}{\setboolean{display}{true}}


% The option printout turns off the `dynamic' features. Can be used to undo a default setting of display.

\DeclareOption{printout}{\setboolean{display}{false}}

\ifthenelse{\boolean{display}}
{\PackageInfo{texpower}{Producing display version. Dynamic features activated.}}
{\PackageInfo{texpower}{Producing printout version. Dynamic features inactive.}}


% The option fixcolorstack switches on a `color stack correction' method which undoes damage to the driver's color stack
% when ``color push'' and ``color pop'' specials are duplicated.

\newboolean{fixcolorstack@TP}
\DeclareOption{fixcolorstack}{\setboolean{fixcolorstack@TP}{true}}


% The option nineminutes sets the page duration of every single page to a high value (of about nine minutes; this seems
% to be a hardcoded upper limit in acrobat 5; see below). This way, a setting in acrobat reader's fullscreen dialogue
% is masked. Otherwise, pages without an explicit page duration setting don't get any page duration setting at all, so
% they will follow the dialogue setting.

\newboolean{nineminutes@TP}
\DeclareOption{nineminutes}{\setboolean{nineminutes@TP}{true}}


%-----------------------------------------------------------------------------------------------------------------------
% Options for setting the base font.

% The option sans makes sans serif the standard Text font.

\newboolean{sans@TP}
\DeclareOption{sans}{\setboolean{sans@TP}{true}}


% The option slifonts makes L. Lamports ``slifonts'' the standard text and math fonts.

\newboolean{slifonts@TP}
\DeclareOption{slifonts}{\setboolean{slifonts@TP}{true}}


%-----------------------------------------------------------------------------------------------------------------------
% Color options.

% The following switch indicates whether color management should be turned on at all.

\newboolean{TPcolor}%                                   Are we using colors at all?


% The option coloremph makes \em and \emph switch the text color instead of the font shape.

\newboolean{coloremph@TP}
\DeclareOption{coloremph}{\setboolean{TPcolor}{true}\setboolean{coloremph@TP}{true}}


% The option colormath makes math formulae be color highlighted.

\newboolean{colormath@TP}
\DeclareOption{colormath}{\setboolean{TPcolor}{true}\setboolean{colormath@TP}{true}}


% The option colorhighlight makes highlighting commands use colors.

\newboolean{colorhighlight@TP}
\DeclareOption{colorhighlight}
{\setboolean{TPcolor}{true}\setboolean{colorhighlight@TP}{true}}


% The option whitebackground selects standard colors for white backgrounds.

\newboolean{whitebackground@TP}
\setboolean{whitebackground@TP}{true}% This is the default.
\DeclareOption{whitebackground}
{\setboolean{TPcolor}{true}\setboolean{whitebackground@TP}{true}}


% The option lightbackground selects standard colors for light (but not white) backgrounds.

\newboolean{lightbackground@TP}
\DeclareOption{lightbackground}
{\setboolean{TPcolor}{true}\setboolean{lightbackground@TP}{true}}


% The option blackbackground selects standard colors for black backgrounds.

\newboolean{blackbackground@TP}
\DeclareOption{blackbackground}
{\setboolean{TPcolor}{true}\setboolean{blackbackground@TP}{true}}


% The option darkbackground selects standard colors for dark (but not black) backgrounds.

\newboolean{darkbackground@TP}
\DeclareOption{darkbackground}
{\setboolean{TPcolor}{true}\setboolean{darkbackground@TP}{true}}


%-----------------------------------------------------------------------------------------------------------------------
% Load the config file for default options.

\InputIfFileExists{/etc/texpower/tpoptions.cfg}{}{}% Allows setting default values for options.


%-----------------------------------------------------------------------------------------------------------------------
% Process options.

\ProcessOptions


%-----------------------------------------------------------------------------------------------------------------------
% General option-driven initialization.

% If the verbose option is set, we give a lot of context information when an error is raised.

\ifthenelse{\boolean{verbose@TP}}{\setcounter{errorcontextlines}{10000}}{}


%-----------------------------------------------------------------------------------------------------------------------
% Driver-specific defaults.

% We provide a switch which (hopefully) allows to distinguish whether postscript specials (as used by PSTricks) can be
% used safely or not.

\newboolean{psspecialsallowed}
\setboolean{psspecialsallowed}{true} % optimistic default

% The switch \ifpdf is to determine whether pdfLaTeX is being run and outputting pdf, using Heiko Oberdiek's faultproof
% pdf detector: 

\IfFileExists{ifpdf.sty}
{%
  \RequirePackage{ifpdf}%
  }
{%
  \@ifundefined{pdftrue}
  {%
  \expandafter\newif\csname ifpdf\endcsname
  \ifx\pdfoutput\undefined
   \else
    \ifx\pdfoutput\relax
     \else
      \ifcase\pdfoutput
       \else
        \pdftrue
       \fi
     \fi
   \fi
   }{}%
   }

\ifpdf\setboolean{psspecialsallowed}{false}\fi

%-----------------------------------------------------------------------------------------------------------------------
% Class-specific defaults.

% The following switches centering of slides off for the slides document class because this would disturb dynamic
% building of slides.

\@ifclassloaded{slides}%                Using the slides document class?
{%
  \ifthenelse{\boolean{display}}%       Dynamic features enabled?
  {\let\@topfil\relax}%                 Then don't center slides.
  {}%
  }
{}


%=======================================================================================================================
% Execute Font options.

\ifthenelse{\boolean{sans@TP}}% Option sans given?
{%
  \renewcommand{\familydefault}{\sfdefault}
}{}

\ifthenelse{\boolean{slifonts@TP}}% Option slifonts given?
{%
  \PackageWarning{texpower}
  {Option slifonts is obsolete.\MessageBreak Loading tpslifonts package instead}%
  \RequirePackage{tpslifonts}
  }
{}


%=======================================================================================================================
% Some registers and macros for general use throughout texpower.sty.

\newcounter{tmpcnta@TP}
\newcounter{tmpcntb@TP}

\newlength{\tempdima@TP}
\newlength{\tempdimb@TP}

\newbox\tempbox@TP

\newboolean{carryon@TP}


% These are needed for calculating the size of the page background box.
\newcommand{\TPpagewidth}{\strip@pt\paperwidth truept}
\newcommand{\TPpageheight}{\strip@pt\paperheight truept}
% \AtBeginDocument
% {%
%   \edef\TPpagewidth{\strip@pt\paperwidth truept}%
%   \edef\TPpageheight{\strip@pt\paperheight truept}%
% }


% \mkfactor{<cs>}{<exp>} is a helper command for automatically generating the fixed point numbers between 0 and 1
% which are employed by the color calculation commands. <exp> can be anything which can stand behind * in calc
% (for instance: \value{counter}/\value{maxcounter} or \ratio or whatever). <cs> should be a valid macro name. <exp>
% is converted into a fixed-point representation which is then assigned to <cs>.
\newcommand{\mkfactor}[2]% 
{\setlength{\tempdima@TP}{1pt*#2}\edef#1{\strip@pt\tempdima@TP}}


% Make a string representation of a length expression.
\newcommand{\mklength@TP}[2]
{\setlength{\tempdima@TP}{#2}\edef#1{\the\tempdima@TP}}

\newcommand{\mklength}{}
\let\mklength\mklength@TP


%=======================================================================================================================
% Color management, color emphasis and highlighting.

%-----------------------------------------------------------------------------------------------------------------------
% Initialization. 

\ifthenelse{\boolean{TPcolor}}{\RequirePackage{color}}{}% If we are to use colors, we need the color package.


%-----------------------------------------------------------------------------------------------------------------------
% Color management kernel. 

\ifthenelse{\boolean{TPcolor}}%                        Only if TeXPower's color management is active.
{% Yes.


  \let\setcolor@TP=\color%                             A hook which can be defined otherwise to turn off colors.


  % Overload \definecolor to store a `driver-independent' copy of the color definition for later use by \colorbetween
  % and relatives. 

  \let\o@definecolor@TP=\definecolor%                  Overload \definecolor.

  \def\definecolor#1#2#3%                              TeXPower's own definition of \definecolor.
  {%
    \o@definecolor@TP{#1}{#2}{#3}%                     Execute original definition.
    \expandafter\edef\csname colordef@TP@#1\endcsname% Make a copy of the color definition.
    {\csname processcolor@TP@#2\endcsname{#3}}%        
    }%


  % Repeat color.sty's standard color definitions to make the original definitions available to TeXPower.

  % begin excerpt from color.sty
  \@ifundefined{c@lor@namefile}{}{\input{\c@lor@namefile}}

  \ifx\color@gray\@undefined
    \ifx\color@rgb\@undefined
    \else
      \definecolor{black}{rgb}{0,0,0}
      \definecolor{white}{rgb}{1,1,1}
    \fi
  \else
    \definecolor{black}{gray}{0}
    \definecolor{white}{gray}{1}
  \fi
  \ifx\color@rgb\@undefined\else
    \definecolor{red}{rgb}{1,0,0}
    \definecolor{green}{rgb}{0,1,0}
    \definecolor{blue}{rgb}{0,0,1}
  \fi
  \ifx\color@cmyk\@undefined\else
    \definecolor{cyan}{cmyk}{1,0,0,0}
    \definecolor{magenta}{cmyk}{0,1,0,0}
    \definecolor{yellow}{cmyk}{0,0,1,0}
  \fi
  % end excerpt from color.sty


  % Commands for calculating new colors.

  \newcommand{\interpolate@TP}[3]%                    Calculate the weighted average between two fixed point values.
  {%
    \setlength{\tempdima@TP}{1pt-#1pt}%               Calculate the second factor for the weighted average.
    \edef\secondfactor@TP{\strip@pt\tempdima@TP}%
    \setlength{\tempdima@TP}{#2pt*\real{#1}+#3pt*\real{\secondfactor@TP}}% Calculate the weighted average.
    \ifthenelse{\lengthtest{\tempdima@TP<0pt}}%       Bound the result to the interval [0,1] (just in case the first
    {\setlength{\tempdima@TP}{0pt}}%                  factor was not from [0,1]).
    {\ifthenelse{\lengthtest{\tempdima@TP>1pt}}{\setlength{\tempdima@TP}{1pt}}{}}%
    \edef\result@TP{\strip@pt\tempdima@TP}%
    }

  \def\interpolate@three@TP#1,#2,#3;#4,#5,#6;#7%      Interpolate a three-piece color value.
  {%
    \interpolate@TP{#7}{#1}{#4}%                      First intermediary value.
    \edef\newcolordef@TP{\result@TP,}%                Store first value.
    \interpolate@TP{#7}{#2}{#5}%                      Second intermediary value.
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store second value.
    \interpolate@TP{#7}{#3}{#6}%                      Third intermediary value.
    \edef\newcolordef@TP{\newcolordef@TP\result@TP}%  Store third value.
    }

  \def\interpolate@four@TP#1,#2,#3,#4;#5,#6,#7,#8;#9% Interpolate a four-piece color value.
  {%
    \interpolate@TP{#9}{#1}{#5}%                      First intermediary value.
    \edef\newcolordef@TP{\result@TP,}%                Store first value.
    \interpolate@TP{#9}{#2}{#6}%                      Second intermediary value.
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store second value.
    \interpolate@TP{#9}{#3}{#7}%                      Third intermediary value.
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store third value.
    \interpolate@TP{#9}{#4}{#8}%                      Fourth intermediary value.
    \edef\newcolordef@TP{\newcolordef@TP\result@TP}%  Store fourth value.
    }

  \def\convert@cmykvalue@rgbvalue@TP#1#2%             Convert one color value from CMYK to rgb.
  {%
    \setlength{\tempdima@TP}{1pt-#1pt-#2pt}%           
    \ifthenelse{\lengthtest{\tempdima@TP<0pt}}{\setlength{\tempdima@TP}{0pt}}{}%
    \edef\result@TP{\strip@pt\tempdima@TP}%
    }%    
    
  \def\convert@cmyk@rgb@TP#1,#2,#3,#4;%               Convert CMYK color to rgb.
  {%
    \convert@cmykvalue@rgbvalue@TP{#1}{#4}%
    \edef\newcolordef@TP{\result@TP,}%                Store first value.
    \convert@cmykvalue@rgbvalue@TP{#2}{#4}%
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store second value.
    \convert@cmykvalue@rgbvalue@TP{#3}{#4}%
    \edef\newcolordef@TP{\newcolordef@TP\result@TP}%  Store third value.
    }

  \def\convert@RGBvalue@rgbvalue@TP#1%                Convert one color value from RGB to rgb.
  {%
    \setlength{\tempdima@TP}{#1pt/255}%
    \edef\result@TP{\strip@pt\tempdima@TP}%
    }%    
    

  \def\convert@RGB@rgb@TP#1,#2,#3;%                   Convert RGB color to rgb.
  {%
    \convert@RGBvalue@rgbvalue@TP{#1}%
    \edef\newcolordef@TP{\result@TP,}%                Store first value.
    \convert@RGBvalue@rgbvalue@TP{#2}%
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store second value.
    \convert@RGBvalue@rgbvalue@TP{#3}%
    \edef\newcolordef@TP{\newcolordef@TP\result@TP}%  Store third value.
    }


  % \colorbetween[<factor>]{<target>}{<source1>}{<source2>} calculates a `weighted average' between two
  % colors. <source1> and <source2> are the names of the two colors. <factor> (default: 0.5) is a fixed-point number
  % between 0 and 1 giving the `weight' for the interpolation between <source1> and <source2>. <target> is the name to
  % be given to the resulting mixed color.
  % If <factor> is 1, then <target> will be identical to <source1> (up to color model conversions, see below), if
  % <factor> is 0, then <target> will be identical to <source2>, if <factor> is 0.5, then <target> will be exactly in
  % the middle between <source1> and <source2>.
  % \colorbetween supports the following color models: rgb, RGB, gray, cmyk, hsb. If both colors are of the same model,
  % the resulting color is also of the respective model. If <source1> and <source2> are from _different_ models, then
  % <target> will _always_ be an rgb color. The only exception is the hsb color model: As I don't know how to convert
  % hsb to rgb, mixing hsb with another color model will always raise an error.
  \newcommand{\colorbetween}[4][.5]% 
  {%
    \begingroup%                               Make the definition of \processcolor... local.
      \newcommand{\processcolor@TP@rgb}[3]%    What if the first color is an rgb color?
      {%
        \ifx##2\processcolor@TP@rgb%           Are both colors rgb colors?
          \interpolate@three@TP##1;##3;{#1}%   Calculate interpolated values.
         \else
          \ifx##2\processcolor@TP@gray%        Is the second color from the gray model?
            \interpolate@three@TP##1;##3,##3,##3;{#1}%    Calculate interpolated values.
           \else
            \ifx##2\processcolor@TP@cmyk%      Is the second color from the cmyk model?
              \convert@cmyk@rgb@TP##3;%        Convert to rgb.
              \edef\newcolordef@TP{\noexpand\interpolate@three@TP##1;\newcolordef@TP;{#1}}%
              \newcolordef@TP
             \else
              \ifx##2\processcolor@TP@RGB%     Is the second color from the RGB model?
                \convert@RGB@rgb@TP##3;%       Convert to rgb.
                \edef\newcolordef@TP{\noexpand\interpolate@three@TP##1;\newcolordef@TP;{#1}}%
                \newcolordef@TP
               \else
                \ifx##2\processcolor@TP@hsb%   Is the second color from the hsb model?
                  \PackageError{texpower}{Don't know how to convert an hsb color!}
                \fi
              \fi
            \fi
          \fi
        \fi
        \edef\newcolordef@TP{{rgb}{\newcolordef@TP}}% Store the result
        }%
      \newcommand{\processcolor@TP@gray}[3]%          What if the first color is a gray color?
      {%
        \ifx##2\processcolor@TP@gray%                 Are both colors gray colors?
          \interpolate@TP{#1}{##1}{##3}%              Calculate interpolated value.
          \edef\newcolordef@TP{{gray}{\result@TP}}%   Store the result
         \else
          \processcolor@TP@rgb{##1,##1,##1}{##2}{##3}% Otherwise, convert first color to rgb and continue.
        \fi
        }%
      \newcommand{\processcolor@TP@cmyk}[3]%          What if the first color is a cmyk color?
      {%
        \ifx##2\processcolor@TP@cmyk%                 Are both colors cmyk colors?
          \interpolate@four@TP##1;##3;{#1}%           Calculate interpolated values.
          \edef\newcolordef@TP{{cmyk}{\newcolordef@TP}}% Store the result
         \else
          \convert@cmyk@rgb@TP##1;%                   Otherwise, convert first color to rgb ...
          \expandafter\processcolor@TP@rgb\expandafter{\newcolordef@TP}{##2}{##3}% ... and continue.
        \fi
        }%
      \newcommand{\processcolor@TP@RGB}[3]%           What if the first color is an RGB color?
      {%
        \convert@RGB@rgb@TP##1;%                      Convert to rgb ...
        \expandafter\processcolor@TP@rgb\expandafter{\newcolordef@TP}{##2}{##3}% ... and continue.
        }%
      \newcommand{\processcolor@TP@hsb}[3]%           What if the first color is an hsb color?
      {%
        \ifx##2\processcolor@TP@hsb%                  Are both colors hsb colors?
          \interpolate@three@TP##1;##3;{#1}%          Calculate interpolated values.
          \edef\newcolordef@TP{{hsb}{\newcolordef@TP}}% Store the result
         \else
          \PackageError{texpower}{Don't know how to convert an hsb color!}
        \fi
        }%
      \expandafter\let\expandafter
      \firstcol@TP\csname colordef@TP@#3\endcsname    % Retrieve definition of color <source1>...
      \expandafter\expandafter\expandafter\firstcol@TP% and apply (remember \processcolor... is part of the definition)
      \csname colordef@TP@#4\endcsname%                 to definition of color <source2>.
      \edef\end@TP%                                     Define color <target> (outside the enclosing group).
      {\endgroup\noexpand\definecolor{#2}\newcolordef@TP}%
    \end@TP
    }% matches \newcommand{\colorbetween}


  \newcommand{\complement@TP}[1]%                   Calculate the complement of a fixed point value.
  {%
    \setlength{\tempdima@TP}{1pt-#1pt}%
    \edef\result@TP{\strip@pt\tempdima@TP}%
    }

  \def\complement@three@TP#1,#2,#3;%                Complement a three-piece color value.
  {%
    \complement@TP{#1}%
    \edef\newcolordef@TP{\result@TP,}%                Store first value.
    \complement@TP{#2}%
    \edef\newcolordef@TP{\newcolordef@TP\result@TP,}% Store second value.
    \complement@TP{#3}% 
    \edef\newcolordef@TP{\newcolordef@TP\result@TP}%  Store third value.
    }

  \def\grabfourth@TP#1,#2,#3,#4;%            Separate the fourth element of a four-piece color value from the rest.
  {%
    \def\mem@TP{#4}%                         Store fourth element.
    \def\result@TP{#1,#2,#3;}%               Store first three elements.
    }

  % \complementcolor{<target>}{<source>} calculates the numerical complement of a color. <source> is the name of the
  % color to be complemented. <target> is the name to be given to the resulting color.
  % \complementcolor supports the following color models: rgb, RGB, gray, cmyk, hsb. 
  \newcommand{\complementcolor}[2]%        
  {%
    \begingroup%                               Make the definition of \processcolor... local.
      \newcommand{\processcolor@TP@rgb}[1]%    What if the color is an rgb color?
      {%
        \complement@three@TP##1;%              Calculate complemented values.
        \edef\newcolordef@TP{{rgb}{\newcolordef@TP}}% Store the result
        }%
      \newcommand{\processcolor@TP@gray}[1]%   What if the color is a gray color?
      {%
        \complement@TP{##1}%                   Calculate complemented value.
        \edef\newcolordef@TP{{gray}{\result@TP}}% Store the result
        }%
      \newcommand{\processcolor@TP@cmyk}[1]%   What if the color is a cmyk color?
      {%
        \grabfourth@TP##1;%                    Remember fourth element.
        \expandafter\complement@three@TP\result@TP%  Calculate complemented values of first three elements.
        \edef\newcolordef@TP{{cmyk}{\newcolordef@TP,\mem@TP}}% Store the result, putting back the fourth element.
        }%
      \newcommand{\processcolor@TP@RGB}[1]%    What if the color is an RGB color?
      {%
        \convert@RGB@rgb@TP##1;%               Convert to rgb ...
        \expandafter\processcolor@TP@rgb\expandafter{\newcolordef@TP}% ... and continue.
        }%
      \newcommand{\processcolor@TP@hsb}[1]%    What if the color is an hsb color?
      {%
        \complement@three@TP##1;%              Calculate complemented values.
        \edef\newcolordef@TP{{hsb}{\newcolordef@TP}}% Store the result
        }%
      \csname colordef@TP@#2\endcsname%        Execute definition of color <source> (which contains \processcolor...)
      \edef\end@TP%                            Define color <target> (outside the enclosing group).
      {\endgroup\noexpand\definecolor{#1}\newcolordef@TP}%
    \end@TP
    }% matches \newcommand{\complementcolor}
  }% matches \ifthenelse{\boolean{TPcolor}}{% Yes.
{% No. Do nothing.
  }

%-----------------------------------------------------------------------------------------------------------------------
% Color name and color set management. 

% \replacecolor[<tset>]{<tcol>}[<sset>]{<scol>} will make <tcol> have the same definition as <scol> (if <scol> is
% defined at all), where <tcol> and <scol> are color names as given in the first argument of \definecolor.  If (one
% of) <tset> and <sset> are given, the colors will be taken from the respective color sets.
\newcommand{\replacecolor}
{%
  \let\replacecolor@hook@TP=\@gobble% This hook can be used for variant checking (see below).
  \replacecolor@TP%                   Pick up arguments.
  }

\newcommand{\replacecolor@TP}[2][]% Pick up the first two arguments of \replacecolor.
{%
  \ifthenelse{\equal{#1}{}}{\edef\tcolname@TP{#2}}{\edef\tcolname@TP{#2@#1}}% Construct `real' target color name.
  \@replacecolor@TP%                                                        Read second argument.
  }%


\ifthenelse{\boolean{TPcolor}}% Only if TeXPower's color management is active.
{% Yes.
  \newcommand{\undefinecolor@TP}[1]%                                Make a color undefined.
  {\expandafter\let\csname\string\color @#1\endcsname=\@undefined}% 


  \newcommand{\ifcolorexists@TP}[3]%                                Conditional for testing whether a color is defined.
  {\@ifundefined{\string\color @#1}{#3}{#2}}%                       Test whether a given color is defined.


  \newcommand{\@replacecolor@TP}[2][]%                              Second part of \replacecolor.
  {%
    \ifthenelse{\equal{#1}{}}{\edef\scolname@TP{#2}}{\edef\scolname@TP{#2@#1}}% Construct `real' source color name.
    \ifcolorexists@TP{\scolname@TP}%                                            Does the source color exist at all?
    {% Yes.
      \replacecolor@hook@TP{\tcolname@TP}%                                      Execute hook.
      \expandafter\let\csname\string\color @\tcolname@TP\expandafter\endcsname% Make value of target color
      \csname\string\color @\scolname@TP\endcsname%                             identical with source color.
      \expandafter\let\csname colordef@TP@\tcolname@TP\expandafter\endcsname%   Make definition of target color
      \csname colordef@TP@\scolname@TP\endcsname%                               identical with source color.
      }%
    {% No. Do nothing.
      }%
    }%


  % The set of TeXPower's `standard colors' and some commands to manipulate them.

  \newcommand{\colors@TP}%             The list of all standard colors defined by texpower.
  {% Initially empty.
    }


  \newcommand{\removecolor@TP}[1]%     Remove a color name from the list.
  {%
    \def\processme@TP##1%              This macro does the real work.
    {%
      \ifthenelse{\equal{#1}{##1}}%    Is this the color to be removed?
      {% Yes. Do nothing, so it vanishes.
        }
      {% No. Re-insert.
        \expandafter\def\expandafter\colors@TP\expandafter{\colors@TP\processme@TP{##1}}%
        }%
      }%
    \expandafter\let\expandafter\colors@TP\expandafter\empty% Initialize \colors@TP.
    \colors@TP%                                               Execute \processme@TP for every color on the list.
    }


  % \addTPcolor{<color>} adds the color named <color> to TeXPower's list of standard colors.
  \newcommand{\addTPcolor}[1]%
  {%
    \removecolor@TP{#1}%               Remove this color from the list (to avoid duplicates).
    \expandafter\def\expandafter\colors@TP\expandafter{\colors@TP\processme@TP{#1}}% ... and insert.
    }


  % \defineTPcolor[<set>]{<name>}{<model>}{<def>} acts like \definecolor{<name>}{<model>}{<def>}, but
  % a. color <name> is automatically added to the list of standard colors and
  % b. if the optional parameter is given, the color is defined in the color set <set> instead of the current color
  %    set. 
  \newcommand{\defineTPcolor}[4][]%    Color definition which also adds the color to the color list.
  {%
    \addTPcolor{#2}%                   Add color to the list.
    \ifthenelse{\equal{#1}{}}%         Color from the current color set?
    {\definecolor{#2}{#3}{#4}}%        Yep. Just define the color.
    {\definecolor{#2@#1}{#3}{#4}}%     No. Add color set identifyer.
    }


  % Some commands for manipluating whole color sets.

  \newcommand{\replacecolors@TP}%                Low level command for replacing a complete color set.          
  {%
    \@ifstar%                                    The starred version will put the color set into normal variant.
    {\let\replacecolor@hook@TP=\register@normalvariant@TP\@replacecolors@TP}
    {\let\replacecolor@hook@TP=\@gobble\@replacecolors@TP}%
    }

  \newcommand{\@replacecolors@TP}[4]%            This part does the real work.
  {%
    \def\processme@TP##1{\replacecolor@TP[#1]{#2##1}[#3]{#4##1}}%
    \colors@TP
    }

  % \usecolorset{<set>} switches to color set <set>.
  \newcommand{\usecolorset}[1]%       
  {%
    \replacecolors@TP*{}{}{#1}{}%   Replace normal variant (registering variants).
    \replacecolors@TP{}{d}{#1}{d}%  Replace dimmed variant.
    \replacecolors@TP{}{e}{#1}{e}%  Replace enhanced variant.
    \color{textcolor}%              Activate textcolor.
    \pagecolor{pagecolor}%          Activate pagecolor.
    }%

  % \dumpcolorset{<set>} saves all standard colors from the current color set to the color set <set>.
  \newcommand{\dumpcolorset}[1]%
  {%
    \nonnormalwarnings@TP{Dumping color set #1}% Output a warning for every color not in the normal variant.
    \replacecolors@TP{#1}{}{}{}%                 Dump normal variant (hopefully).
    \replacecolors@TP{#1}{d}{}{d}%               Dump dimmed variant.
    \replacecolors@TP{#1}{e}{}{e}%               Dump enhanced variant.
    }%


  % Commands for color variants.

  \newcommand{\registervariant@TP}[2]%           Remember which variant a color is currently in.
  {\expandafter\def\csname cvar@#1@TP\endcsname{#2}}

  \newcommand{\register@normalvariant@TP}[1]%    Register that a color is now in the normal variant.
  {\registervariant@TP{#1}{}}

  \newcommand{\currentvariant@TP}[1]%            Return the current variant of a color.
  {\csname cvar@#1@TP\endcsname}
  
  \newcommand{\ifnormalvariant@TP}[3]%           Conditional for checking whether a color is in the normal variant.
  {\ifthenelse{\equal{\currentvariant@TP{#1}}{}}{#2}{#3}}
  
  \newcommand{\nonnormalwarnings@TP}[1]%         Checks the current variant for every standard color and gives a warning
  {%                                             if it's not the normal one.
    \def\processme@TP##1%
    {%
      \ifnormalvariant@TP{##1}{}
      {%
        \PackageWarning{texpower}
        {#1\MessageBreak when color ##1 is in \currentvariant@TP{##1} variant}%
        }%
      }%
    \colors@TP
    }
  

  % Default dim level for automatic color dimming.
  \newcommand{\dimlevel}{.7}

  % \dimcolor[<level>]{<color>} dims the color named <color>. It checks whether an explicit `dimmed' variant d<color>
  % exists. If yes, <color> is replaced by d<color>. Otherwise, the dimmed color is calculated by interpolating between
  % pagecolor and <color>. The parameter for \colorbetween is given by the optional argument <level> (default:
  % \dimlevel). 
  \newcommand{\dimcolor}[2][\dimlevel]
  {%
    \ifnormalvariant@TP{#2}%            Color in the normal variant?
    {% Yes.
      \registervariant@TP{#2}{d}%       Register dimmed variant.
      \ifcolorexists@TP{d#2}%           Dedicated dimmed color found?
      {\replacecolor{#2}{d#2}}%         Yes. use that one.
      {\colorbetween[#1]{#2}{pagecolor}{#2}}% No. Dim numerically using \colorbetween.
      }%
    {}% No. Do nothing.
    }

  % \dimcolors[<level>] dims all standard colors using \dimcolor. See the description of \dimcolor for details.
  \newcommand{\dimcolors}[1][\dimlevel]
  {%
    \def\processme@TP##1{\dimcolor[#1]{##1}}%
    \colors@TP
    }%
  

  % Default enhance level for automatic color enhancing.
  \newcommand{\enhancelevel}{.5}

  % \enhancecolor[<level>]{<color>} enhances the color named <color>. It checks whether an explicit `enhanced' variant
  % e<color> exists. If yes, <color> is replaced by e<color>. Otherwise, the enhanced color is calculated by
  % `extrapolating' from pagecolor and <color>. The parameter for \colorbetween is given by the optional argument
  % <level> (default: \enhancelevel).  
  \newcommand{\enhancecolor}[2][\enhancelevel]
  {%
    \ifnormalvariant@TP{#2}%            Color in the normal variant?
    {%
      \registervariant@TP{#2}{e}%       Register enhanced variant.
      \ifcolorexists@TP{e#2}%           Dedicated enhanced color found?
      {\replacecolor{#2}{e#2}}%         Yes. use that one.
      {\colorbetween[-#1]{#2}{pagecolor}{#2}}% No. Enhance numerically using \colorbetween.
      }%
    {}%
    }%

  % \enhancecolors[<level>] enhances all standard colors using \enhancecolor. See the description of \enhancecolor for
  % details. 
  \newcommand{\enhancecolors}[1][\enhancelevel]
  {%
    \def\processme@TP##1{\enhancecolor[#1]{##1}}%
    \colors@TP
    }%


  \newcommand{\replacecolorsbyone@TP}[2]%            Replace all colors from the current color set by a single color.
  {%
    \def\processme@TP##1{\replacecolor{#1##1}{#2}}%
    \colors@TP
    }

  % The color used to make things `vanish'.
  \newcommand{\vanishcolor}{pagecolor}

  % \vanishcolors replaces all standard colors by \vanishcolor.
  \newcommand{\vanishcolors}[1][\vanishcolor]{\replacecolorsbyone@TP{}{#1}}


  % TeXPower's predefined color sets and commands to activate them. Redefine in /etc/texpower/tpcolors.cfg as convenient. 

  \input{/etc/texpower/tpcolors.cfg}


  % \whitebackground sets the standard colors up for white background.
  \newcommand{\whitebackground}% 
  {%
    \usecolorset{whitebg}%
    }

  % When the whitebackground option (or no background option, but some other color-activating option like colormath) is
  % given, \whitebackground is executed automatically. 
  \ifthenelse{\boolean{whitebackground@TP}}
  {\AtEndOfPackage{\whitebackground}}%                    Execute after texpower.cfg was read (for redefinitions).
  {}

  % \lightbackground sets the standard colors up for `light' background.
  \newcommand{\lightbackground}% 
  {%
    \usecolorset{lightbg}%
    }

  % When the lightbackground option is given, \lightbackground is executed automatically. 
  \ifthenelse{\boolean{lightbackground@TP}}{\AtEndOfPackage{\lightbackground}}{}

  % \darkbackground sets the standard colors up for `dark' background.
  \newcommand{\darkbackground}%
  {%
    \usecolorset{darkbg}%
    }
  
  % Execute \darkbackground automatically if the darkbackground option was given.
  \ifthenelse{\boolean{darkbackground@TP}}{\AtEndOfPackage{\darkbackground}}{}

  % \blackbackground sets the standard colors up for black background.
  \newcommand{\blackbackground}%
  {%
    \usecolorset{blackbg}%
    }

  % Execute \blackbackground automatically if the blackbackground option was given.
  \ifthenelse{\boolean{blackbackground@TP}}{\AtEndOfPackage{\blackbackground}}{}

  \ifthenelse{\boolean{TPcolor}}{\AtEndOfPackage{\color{textcolor}\let\default@color\current@color}}{}

  % If TeXPower's color management is active, set page and text color at the beginning of the document.
  \ifthenelse{\boolean{TPcolor}}{\AtBeginDocument{\pagecolor{pagecolor}\color{textcolor}}}{}
  }% matches \ifthenelse{\boolean{TPcolor}}{% Yes.
{% No; provide dummies.
  \let\setcolor@TP=\@gobble%
  \newcommand{\@replacecolor@TP}[2][]{}%                                         
  \let\addTPcolor=\@gobble
  \newcommand{\defineTPcolor}[4][]{}%            
  \let\usecolorset=\@gobble
  \let\dumpcolorset=\@gobble
  \newcommand{\dimcolor}[2][]{}
  \newcommand{\dimcolors}[1][]{}
  \newcommand{\enhancecolor}[2][]{}
  \newcommand{\enhancecolors}[1][]{}
  \newcommand{\vanishcolors}[1][]{}
  }


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of the coloremph option.

\ifthenelse{\boolean{coloremph@TP}}%                       Should \emph use color?
{%  Yes;
  \DeclareRobustCommand{\em}%                              Redefine \em.
  {%
    \@nomath\em \color{emcolor}%                           Change color.
    \replacecolor{tmp@TP}{emcolor}%                        Exchange emcolor and altemcolor.
    \replacecolor{emcolor}{altemcolor}%
    \replacecolor{altemcolor}{tmp@TP}%
    }%
  }%
{}% No; keep original definition.


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of the colormath option.
% Note that the following code is quite fragile and contains some modifications of LaTeX internals. Thus it is likely to
% cause trouble, especially in conjunction with other packages modifying the LaTeX kernel. The array package is
% supported, but no explicit support of other packages exists. If you experience strange and inexplicable errors while
% the colormath option is active, first of all try switching it off to see whether anything changes. 
% The implementation of colormath is likely to change several times before the first beta release, so expect backward
% incompatible changes in behaviour.

\ifthenelse{\boolean{colormath@TP}}%                       Should we color math?
{%  Yes.
  \AtBeginDocument
  {%
    % The most basic magical incantation: Color inline math using \everymath. Beware of side effects of this hack.
    \expandafter\everymath\expandafter{\the\everymath\color{mathcolor}}% 
    % Color displayed math by overloading LaTeX's own math environments. Note that this doesn't work for the TeX
    % notation $$, which is deprecated in LaTeX anyway. 
    % Note further that for the eqnarray and eqnarray* environments, the current implementation places the color change
    % command OUTSIDE the math environment (for technical reasons; maybe this can be remedied by a more sophisticated
    % implementation), which will almost invariably lead to unwanted extra vertical space before and after equation
    % arrays. Currently there is no clean remedy, apart from using amsmath's align environment.
    \let\o@dm@TP=\[%                                      Save the original definitions of begin and end macros for 
    \let\o@enddm@TP=\]%                                   LaTeX's displayed math environments.
    \let\o@eqa@TP=\eqnarray%
    \let\o@endeqa@TP=\endeqnarray%
    \expandafter\let\expandafter\o@eqastar@TP\csname eqnarray*\endcsname%
    \expandafter\let\expandafter\o@endeqastar@TP\csname endeqnarray*\endcsname%
    \def\[{\o@dm@TP\begingroup\color{mathcolor}}%         Redefine the begin and end macros for LaTeX's displayed math
    \def\]{\endgroup\o@enddm@TP}%                         environments, adding the color change commands and an extra
    \def\eqnarray{\begingroup\color{mathcolor}\o@eqa@TP}% level of grouping.
    \def\endeqnarray{\o@endeqa@TP\endgroup\@ignoretrue}%
    \@namedef{eqnarray*}{\begingroup\color{mathcolor}\o@eqastar@TP}
    \@namedef{endeqnarray*}{\o@endeqastar@TP\endgroup\@ignoretrue}
    \@ifpackageloaded{amsmath}%                            Amsmath's displayed math environments are covered by the
    {%                                                     \everymath hack because they are `fake' displayed equations.
      \@ifpackagelater{amsmath}{2000/01/15}%                 As amsmath 1.x redefines the equation environment to be a 
      {%                                                     variant of gather, treating it as a displayed math 
        \let\o@eq@TP=\equation%                              environment would lead to problems, so this redefinition is 
        \let\o@endeq@TP=\endequation%                        made only if amsmath 1.x is not loaded.
        \def\equation{\o@eq@TP\begingroup\color{mathcolor}}% 
        \def\endequation{\endgroup\everymath{}\o@endeq@TP}%  
      }%
    {}%
    }%
  {%
    \let\o@eq@TP=\equation%                   
    \let\o@endeq@TP=\endequation%             
    \def\equation{\o@eq@TP\begingroup\color{mathcolor}}% 
    \def\endequation{\endgroup\everymath{}\o@endeq@TP}%  
    }%
  }% matches \AtBeginDocument{
  %
  % Sometimes, a math environment is used for something other than displaying math. The macro \origmath will put its
  % argument in math mode, but turn off coloring. If another math environemt should be nested inside the argument of
  % \origmath, it will be coloured. 
  \newcommand{\origmath}[1]{{\everymath{}\ensuremath{\everymath{\color{mathcolor}}#1}}}%
  %
  % We need to redefine some LaTeX macros which internally use math mode, to make sure that not all tabulars and
  % parboxes are coloured. Note that this can break packages which mess with tabular themselves.
  \renewcommand*\labelitemi{\origmath{\m@th\bullet}}%
  \@ifpackageloaded{array}%                           The array package redefines \@tabular
  {%
    \def\@tabular{%
      \leavevmode
      \hbox \bgroup \everymath{}$\everymath{\color{mathcolor}}\col@sep\tabcolsep \let\d@llarbegin\begingroup % $
      \let\d@llarend\endgroup
      \@tabarray
    }%
    \@ifpackageloaded{colortbl}
    {%
      \def\@classz{\@classx
        \@tempcnta \count@
        \prepnext@tok
        \expandafter\CT@extract\the\toks\@tempcnta\columncolor!\@nil
        \@addtopreamble{%
          \setbox\z@\hbox\bgroup\bgroup
          \ifcase \@chnum
          \hskip\stretch{.5}\kern\z@
          \d@llarbegin
          \insert@column
          \d@llarend\hskip\stretch{.5}\or
          \d@llarbegin \insert@column \d@llarend \hfill \or
          \hfill\kern\z@ \d@llarbegin \insert@column \d@llarend \or
          \@startvcenter
          \@startpbox{\@nextchar}\insert@column \@endpbox $\or % $
          \vtop \@startpbox{\@nextchar}\insert@column \@endpbox \or
          \vbox \@startpbox{\@nextchar}\insert@column \@endpbox
          \fi
          \egroup\egroup
          \begingroup
          \CT@setup
          \CT@column@color
          \CT@row@color
          \CT@do@color
          \endgroup
          \@tempdima\ht\z@
          \advance\@tempdima\minrowclearance
          \vrule\@height\@tempdima\@width\z@
          \unhbox\z@}%
        \prepnext@tok}%
    }
    {%
      \def\@classz{\@classx
        \@tempcnta \count@
        \prepnext@tok
        \@addtopreamble{\ifcase \@chnum
          \hfil
          \d@llarbegin
          \insert@column
          \d@llarend \hfil \or
          \hskip1sp\d@llarbegin \insert@column \d@llarend \hfil \or
          \hfil\hskip1sp\d@llarbegin \insert@column \d@llarend \or
          \@startvcenter
          \@startpbox{\@nextchar}\insert@column \@endpbox $\or        % $
          \vtop \@startpbox{\@nextchar}\insert@column \@endpbox \or
          \vbox \@startpbox{\@nextchar}\insert@column \@endpbox
          \fi}\prepnext@tok}%
    }
    \def\@startvcenter{\everymath{}$\everymath{\color{mathcolor}}\vcenter}% $
    \expandafter\def\expandafter\@mkpream\expandafter#\expandafter1%
    \expandafter{%
      \expandafter\let\expandafter\@startvbox\expandafter\relax
      \@mkpream{#1}}
  }
  {%
    \def\@tabular{\leavevmode \hbox \bgroup \everymath{}$\everymath{\color{mathcolor}}\let\@acol\@tabacol
      \let\@classz\@tabclassz
      \let\@classiv\@tabclassiv \let\\\@tabularcr\@tabarray% $
      }%
    }
  \long\def\@iiiparbox#1#2[#3]#4#5{%
    \leavevmode
    \@pboxswfalse
    \setlength\@tempdima{#4}%
    \@begin@tempboxa\vbox{\hsize\@tempdima\@parboxrestore#5\@@par}%
    \ifx\@empty#2\else\ifx\relax#2\else
      \setlength\@tempdimb{#2}%
      \def\@parboxto{to\@tempdimb}%
    \fi\fi
    \if#1b\vbox
      \else\if #1t\vtop
      \else\ifmmode\vcenter
      \else\@pboxswtrue \everymath{}$\everymath{\color{mathcolor}}\vcenter
    \fi\fi\fi
    \@parboxto{\let\hss\vss\let\unhbox\unvbox
      \csname bm@#3\endcsname}%
    \if@pboxsw \m@th$\fi
    \@end@tempboxa}
  \let\o@textsuperscript@TP=\textsuperscript
  \def\textsuperscript#1{{\everymath{}\o@textsuperscript@TP{\everymath{\color{mathcolor}}#1}}}%
  }% matches \ifthenelse{\boolean{colormath@TP}}{%  Yes.
{% No; keep original definition.
  \let\origmath=\ensuremath%      \origmath needs to have a sensible definition.
}

%-----------------------------------------------------------------------------------------------------------------------
% New highlighting and emphasis commands. Most of them have a sensible alternative definition if the colorhighlight
% option is not given.

% \code{<text>} will display <text> in a `code-like' style (for shell commands or macro names).
% \codeswitch switches to the style used by \code, for use e.g. in verbatim environments.
\ifthenelse{\boolean{colorhighlight@TP}}%                Color highlighting enabled?
{%  Yes; code is displayed typewriter-style, bold and in a special color.
  \DeclareRobustCommand{\code}[1]{\textcolor{codecolor}{\textbf{\texttt{#1}}}}%
  \DeclareRobustCommand{\codeswitch}{\color{codecolor}\bfseries\ttfamily}% 
  }
{%  No; code is displayed just in typewriter-style and bold.
  \DeclareRobustCommand{\code}[1]{\textbf{\texttt{#1}}}%
  \DeclareRobustCommand{\codeswitch}{\bfseries\ttfamily}%  
  }

% \macroname{<text>} acts like \code, but adds a backslash in front.
\newcommand{\macroname}[1]{\code{\textbackslash#1}}

% \commandapp[<opt>]{<name>}{<arg>} displays a macro with an argument. <name> is the macro name, <opt> is an optional
% argument, <arg> is the macro argument. Note that only one pair of braces is added for <arg>; for several arguments,
% \}\{ needs to be used inside <arg> to separate arguments.
\newcommand{\commandapp}[3][]{\code{\macroname{#2}\ifthenelse{\equal{#1}{}}{}{[#1]}\{#3\}}}

% \carg{<text>} displays a `symbolic argument', i.e. <text> in code style enclosed in pointy braces.
\newcommand{\carg}[1]{\code{\origmath{\left<\code{#1}\right>}}}


% \underline{<text>} emphasises <text> using a special color if the colorhighlight option is given and by boldfacing
% otherwise. 
\ifthenelse{\boolean{colorhighlight@TP}}%                  Color highlighting enabled?
{%  Yes;
  \DeclareRobustCommand{\underl}{\textcolor{underlcolor}}% Use color to highlight.
  }
{%  No;
  \DeclareRobustCommand{\underl}{\textbf}%                 Use bold face.
  }


% \concept{<text>} emphasises <text> using a special color if the colorhighlight option is given and by boldfacing
% otherwise. To be used for emphasizing names of (new) concepts.
\ifthenelse{\boolean{colorhighlight@TP}}%                  Color highlighting enabled?
{%  Yes;
  \DeclareRobustCommand{\concept}{\textcolor{conceptcolor}}% Use color to highlight.
  }
{%  No;
  \DeclareRobustCommand{\concept}{\textbf}%                  Use bold face.
  }


% \inactive{<text>} emphasises <text> using a special color if the colorhighlight option is given. Nothing is done if
% the option is not given. To be used for `de-emphasizing' things not currently of interest.
\ifthenelse{\boolean{colorhighlight@TP}}%                  Color highlighting enabled?
{%  Yes;
  \DeclareRobustCommand{\inactive}{\textcolor{inactivecolor}}% Use color to highlight.
  }
{%  No;
  \DeclareRobustCommand{\inactive}{\monochromeinactive}%       Use monochrome default.
  }

\providecommand{\monochromeinactive}{}% What should \inactive do if colors can't be used? We provide a hook for
                                      % user definitions.


% \present[<opt>]{<text>} puts its argument into an \fbox with coloured background.
% If <opt> is given, it is added to the left of the box without taking any space, i.e. it will overlap text to the left
% of the box. This addition is useful mainly for adding `constraints' to things presented in a description or center
% environment. 
\ifthenelse{\boolean{colorhighlight@TP}}%                  Color highlighting enabled?
{%  Yes; use a colored box.
  \newcommand{\present}[2][]{\leavevmode\llap{\textbf{\footnotesize#1}\,}\fcolorbox{textcolor}{presentcolor}{#2}}%
  \newcommand{\mkpbox@TP}[1]{\fcolorbox{presentcolor}{presentcolor}{#1}}% Internal macro for use by \presentbox.
  }
{%  No; use an \fbox.
  \newcommand{\present}[2][]{\leavevmode\llap{\textbf{\footnotesize#1}\,}\fbox{#2}}%
  \newcommand{\mkpbox@TP}[1]{\fbox{#1}}%
  }

% \begin{presentbox} <stuff> \end{presentbox}
% creates a coloured patch of width \linewidth with a minipage containing <stuff> inside. If the colorhighlight option
% is not given, an \fbox containing the minipage is created.
\newsavebox{\pbox@TP}%                                  Container for the minipage to be boxed.
\newenvironment{presentbox}%
{%
  \par\smallskip%                                       First a small space to separate the area from preceding text.
  \begin{lrbox}{\pbox@TP}%                              Save the contents in a minipage inside \pbox@TP.
    \noindent
    \begin{minipage}{\linewidth-2\fboxsep-2\fboxrule}%  Reduce the width of the minipage to leave space for the frame.
      \replacecolor{presentcolor}{pagecolor}%           If \present is used inside the colored area...
      }%
    {%
    \end{minipage}
  \end{lrbox}%
  \noindent\mkpbox@TP{\usebox{\pbox@TP}}%               This typesets the saved minipage inside the coloured area.
  \smallskip%                                           A small space to separate the area from succeding text.
  \par
  }


%=======================================================================================================================
% Structured rules, box and page backgrounds.

%-----------------------------------------------------------------------------------------------------------------------
% Structured rules.

% Some configurable defaults for rules and box backgrounds.

% Default number of stripes for gradient rules and box backgrounds.
\newcommand{\rulestripes}{10}

% Default stripe overlap for avoiding `gaps' in color gradients.
\newcommand{\stripeoverlap}{.15pt}

% Default gradient progression for rules and box backgrounds (single gradients or first part of double gradients).
\newcommand{\rulefirstgradprogression}{1}

% Default gradient progression for rules and box backgrounds (second part of double gradients).
\newcommand{\rulesecondgradprogression}{1}

% Default position of the `middle' color of a double gradient.
\newcommand{\rulegradmidpoint}{.5}


% The following are used internally when making color gradients.

\newcounter{stripe@TP}

\newcounter{stripes@TP}

\newcommand{\firstgradprogression@TP}{1}

\newcommand{\secondgradprogression@TP}{1}

\newcounter{gradprogression@TP}

\newcommand{\gradmidpoint@TP}{.5}


% Special versions of \mkfactor which apply gradient progressions.

\newcommand{\mkgradfirstfactor@TP}{\mkgradfactor@TP\firstgradprogression@TP}

\newcommand{\mkgradsecondfactor@TP}{\mkgradfactor@TP\secondgradprogression@TP}

\newcommand{\mkgradfactor@TP}[3]% Calculate a factor modified by a `progression' parameter.
{%
  \mkfactor{#2}{#3}%                               Calculate the unmodified factor.
  \setcounter{gradprogression@TP}{#1}%             Factor definition may contain a calc-expression.
  \ifthenelse{\value{gradprogression@TP}=1}{}%     Progression value 1 is neutral.
  {%
    \ifthenelse{\value{gradprogression@TP}<0}%     `Negative' progression?
    {% Yes.
      \@tempcnta-\value{gradprogression@TP}\relax% Complement progression wrt 0.
      \mkfactor{#2}{1-1pt*\real{#2}}%              Complement factor definition wrt 1pt.
      }
    {\@tempcnta\value{gradprogression@TP}\relax}%  No; Use progression as given.
    \whiledo{\the\@tempcnta>1}%                    Calculate (factor definition)^(progression).
    {\advance\@tempcnta by -1\relax\mkfactor{#2}{\real{#2}*\real{#2}}}%
    \ifthenelse{\value{gradprogression@TP}<0}%     `Negative' progression?
    {% Yes.
      \mkfactor{#2}{1-1pt*\real{#2}}%              Complement result wrt 1pt.
      }
    {}%
  }%
}


% \vgradrule[<stripes>][<startmodel>]{<startcolor>}[<endmodel>]{<endcolor>}[<raise>]{<width>}{<height>} creates a
% rule-like object consisting of a vertical color gradient composed of horizontal stripes.
%
% The topmost stripe has color {<startcolor>}, the bottommost stripe has color {<endcolor>}. Inbetween, color changes
% gradually from top to bottom.
% The colors are specified exactly as for the \color command: if the optional argument <startmodel> is given,
% <startcolor> contains an explicit definition of a color from model <startmodel>, otherwise <startcolor> is the name of
% a defined color. The same holds for <endmodel> and <endcolor>.
% 
% The arguments [<raise>]{<width>}{<height>} work exactly as for the \rule command.
% 
% The optional argument <stripes>, if given, should contain a (calc expression for a) number specifying the number of
% stripes. If <stripes> is not given, the default is the content of \rulestripes (default 10).
% 
% There is one more parameter which is not given as an argument. The control sequence \rulefirstgradprogression should
% expand to an (calc expression for an) integer. This value (default 1) controls the `order' of progression from
% <startcolor> to <endcolor>.
% The default value 1 means linear progression. 2 means quadratic progression, i.e. color values `nearer' to <endcolor>
% are reached `later' (the square of 0.5, for instance, is 0.25, i.e. in the geometric middle point of the rule
% produced, the color gradient will have traveled only to one quarter of the `distance' between <startcolor> and
% <endcolor>). 
% 3 means cubic progression and so on. 0 and -1 mean the same as 1. -2 means quadratic progression ``from bottom to
% top'', i.e. color values `nearer' to <endcolor> are reached `earlier', and analogously for -3, -4, ... 
% 
% If you wish to give the second optional argument but not the first, just write \vgradrule[][<startmodel>]...
% 
\newcommand{\vgradrule}[1][]% Pick up first optional argument: [<stripes>]
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameter for rules.
  \ifthenelse{\equal{#1}{}}%                               First optional argument given?
  {\setcounter{stripes@TP}{\rulestripes}}%                 No; use default value.
  {\setcounter{stripes@TP}{#1}}%                           Yes.
  \vgradrule@TP%                                           Pick up [<startmodel>]{<startcolor>}.
}

\newcommand{\vgradrule@TP}[2][]% Pick up next pair of arguments: [<startmodel>]{<startcolor>}.
{%
  \ifthenelse{\equal{#1}{}}%               <startmodel> given?
  {\replacecolor{startcolor@TP}{#2}}%      No; <startcolor> is a color name.
  {\definecolor{startcolor@TP}{#1}{#2}}%   Yes; {<startmodel>}{<startcolor>} is a color definition.
  \@vgradrule@TP%                          Pick up [<endmodel>]{<endcolor>}.
}

\newcommand{\@vgradrule@TP}[2][]% Pick up next pair of arguments: [<endmodel>]{<endcolor>}.
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{endcolor@TP}{#2}}
  {\definecolor{endcolor@TP}{#1}{#2}}%
  \@@vgradrule@TP%                         Pick up rule arguments and proceed.
}

\newcommand{\hstripe@TP}[4]%               Helper command for making _one_ stripe. Can be overladed for making historams.
{\hbox{{\setcolor@TP{stripecolor@TP}\rule{#2}{#3}}}#4}

\newcommand{\@@vgradrule@TP}[3][0pt]%      Main part of \vgradrule.
{%
  \ifthenelse{\value{stripes@TP}<2}%       A `pathological case' which can happen in animations: If 0 or 1 stripes are
                                   %       requested, a division by zero error would be produced by the gradient code.
  {\mbox{{\setcolor@TP{startcolor@TP}\rule[#1]{#2}{#3}}}}% In this case, just produce a colored rule.
  {%
    \raisebox{#1}%                         Evaluate the <raise> argument of the rule.
    {%
      \vbox%                               A vbox with \offinterlineskip allows to align the stripes vertically.
      {%
        \offinterlineskip
        \setcounter{stripe@TP}{0}%         Initialize the number of the current stripe.
        \whiledo{\value{stripe@TP}<\value{stripes@TP}}
        {%
          \mkgradfirstfactor@TP{\tmp@TP}%  Make the weight for \colorbetween, based on the number of the current stripe
          {\value{stripe@TP}/(\value{stripes@TP}-1)}% and the first gradient progression.
          \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{startcolor@TP}% Calculate stripe color.
          \stepcounter{stripe@TP}%
          \ifthenelse{\value{stripe@TP}=\value{stripes@TP}}%     Last stripe?
          {\hstripe@TP{\tmp@TP}{#2}{(#3)/\value{stripes@TP}}{}}% Yes; make stripe w/o overlap.
          {%                                                     No; add a kern to make stripes overlap.
            \hstripe@TP{\tmp@TP}{#2}{(#3)/\value{stripes@TP}+\stripeoverlap}{\kern-\stripeoverlap}%
            }%
          }% matches \whiledo{\value{stripe@TP}<\value{stripes@TP}}{%
        }% matches \vbox{%
      }% matches \raisebox{#1}{%
    }% matches second argument of \ifthenelse{\value{stripes@TP}<2}
  }% matches \newcommand{\@@vgradrule@TP}[3][0pt]{%


% \dblvgradrule[<midpoint>][<stripes>]
% [<startmodel>]{<startcolor>}[<midmodel>]{<midcolor>}[<endmodel>]{<endcolor>}
% [<raise>]{<width>}{<height>}
% creates a rule-like object consisting of a vertical color gradient composed of horizontal stripes.
% 
% The behaviour is exactly like \vgradrule, only in addition to the defined `start' and `end' color, there is an
% additional defined `middle' color. The color gradient first progresses from the start to the middle color and then
% from the middle to the end color.
%
% [<midmodel>]{<midcolor>} specify the middle color exactly as described for the other colors in the description of
% \vgradrule.
%
% The additional optional parameter <midpoint> is a fixed-point value specifying where in the produced gradient the
% middle color is placed. 0 means the middle color replaces the start color; 1 means the middle color replaces the end
% color; 0.5 means the middle color is placed in the geometric middle between start and end color. If <midpoint> is not
% given, the default is the content of \rulegradmidpoint (default 0.5).
%
% There is another parameter not passed as an argument: while \rulefirstgradprogression specifies the order of
% progression from first to middle color as described for \vgradrule, \rulesecondgradprogression specifies the order of
% progression from middle to end color.
% 
% If you wish to give one from the first row of optional arguments but not the other(s), any one can be replaced by []
% to use the default.
% 
\newcommand{\dblvgradrule}[1][]% Pick up first optional argument: [<midpoint>]
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameters for rules.
  \let\secondgradprogression@TP=\rulesecondgradprogression
  \ifthenelse{\equal{#1}{}}%                               First optional argument given?
  {\let\gradmidpoint@TP=\rulegradmidpoint}%                No; use default value.
  {\def\gradmidpoint@TP{#1}}%                              Yes.
  \dblvgradrule@TP%                                        Pick up second optional argument.
}

\newcommand{\dblvgradrule@TP}[1][]% Pick up second optional argument: [<stripes>]
{%
  \ifthenelse{\equal{#1}{}}
  {\setcounter{stripes@TP}{\rulestripes}}
  {\setcounter{stripes@TP}{#1}}%
  \@dblvgradrule@TP
}

\newcommand{\@dblvgradrule@TP}[2][]% Pick up next pair of arguments: [<startmodel>]{<startcolor>}.
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{startcolor@TP}{#2}}
  {\definecolor{startcolor@TP}{#1}{#2}}%
  \@@dblvgradrule@TP
}

\newcommand{\@@dblvgradrule@TP}[2][]% Pick up next pair of arguments: [<midmodel>]{<midcolor>}.
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{midcolor@TP}{#2}}
  {\definecolor{midcolor@TP}{#1}{#2}}%
  \@@@dblvgradrule@TP
}

\newcommand{\@@@dblvgradrule@TP}[2][]% Pick up next pair of arguments: [<endmodel>]{<endcolor>}.
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{endcolor@TP}{#2}}
  {\definecolor{endcolor@TP}{#1}{#2}}%
  \@@@@dblvgradrule@TP%                         Pick up rule arguments and proceed.
}

\newcommand{\@@@@dblvgradrule@TP}[3][0pt]%              Main part of \dblvgradrule.
{%
  \ifthenelse{\value{stripes@TP}<2}%                    The gradient code is not equipped for making less than 2 stripes.
  {\mbox{{\setcolor@TP{midcolor@TP}\rule[#1]{#2}{#3}}}}% In this case, just produce a rule colored with the middle color.
  {%
    \raisebox{#1}%                                      Evaluate the <raise> argument of the rule.
    {%
      \vbox%                                            A vbox with \offinterlineskip allows to align the stripes
      {%                                                vertically.
        \offinterlineskip
        \setcounter{stripe@TP}{0}%                      Initialize the number of the current stripe.
        \setcounter{tmpcnta@TP}%                        Number of the `middle' stripe.
        {\value{stripes@TP}*\real{\gradmidpoint@TP}}%
        \whiledo{\value{stripe@TP}<\value{tmpcnta@TP}}% Produce the upper part of the gradient.
        {%
          \mkgradfirstfactor@TP{\tmp@TP}%               Make the weight for \colorbetween, based on the number of the 
          {\value{stripe@TP}/\value{tmpcnta@TP}}%       current stripe and the first gradient progression.
          \colorbetween[\tmp@TP]{stripecolor@TP}{midcolor@TP}{startcolor@TP}% Calculate stripe color.
          \hstripe@TP{\tmp@TP}%                                               Make stripe with overlap.
          {#2}{(#3)/\value{stripes@TP}+\stripeoverlap}{\kern-\stripeoverlap}% This is the upper part, remember?
          \stepcounter{stripe@TP}%
          }%
        \stepcounter{tmpcnta@TP}%
        \ifthenelse{\value{stripes@TP}=\value{tmpcnta@TP}}% Only one stripe left to produce?
        {\hstripe@TP{1}{#2}{(#3)/\value{stripes@TP}}{}}%    Just produce one stripe colored with the end color.
        {%
          \whiledo{\value{stripe@TP}<\value{stripes@TP}}%   Produce the lower part of the gradient.
          {%
            \mkgradsecondfactor@TP{\tmp@TP}%                Make the weight for \colorbetween.
            {(\value{stripe@TP}-\value{tmpcnta@TP}+1)/(\value{stripes@TP}-\value{tmpcnta@TP})}%
            \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{midcolor@TP}% Calculate stripe color.
            \stepcounter{stripe@TP}%
            \ifthenelse{\value{stripe@TP}=\value{stripes@TP}}%     Last stripe?
            {\hstripe@TP{\tmp@TP}{#2}{(#3)/\value{stripes@TP}}{}}% Yes; make stripe w/o overlap.
            {%                                                     No; add kern to make stripes overlap.
              \hstripe@TP{\tmp@TP}{#2}{(#3)/\value{stripes@TP}+\stripeoverlap}{\kern-\stripeoverlap}%
              }%
            }% matches \whiledo{\value{stripe@TP}<\value{stripes@TP}}%
          }% matches second argument of \ifthenelse{\value{stripes@TP}=\value{tmpcnta@TP}}%
        }% matches \vbox{%
      }% matches \raisebox{#1}{%
    }% matches second argument of \ifthenelse{\value{stripes@TP}<2}%
  }% matches \newcommand{\@@@@dblvgradrule@TP}[3][0pt]%


% \hgradrule[<stripes>][<startmodel>]{<startcolor>}[<endmodel>]{<endcolor>}[<raise>]{<width>}{<height>} creates a
% rule-like object consisting of a horizontal color gradient composed of vertical stripes.
%
% Parameters are exactly as those for \vgradrule (replacing `top' by `left' and `bottom' by `right'). See there for
% explanations. 
%
\newcommand{\hgradrule}[1][]% Pick up first optional argument: [<stripes>].
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameter for rules.
  \ifthenelse{\equal{#1}{}}%                               First optional argument given?
  {\setcounter{stripes@TP}{\rulestripes}}%                 No; use default value.
  {\setcounter{stripes@TP}{#1}}%                           Yes.
  \hgradrule@TP%                                           Pick up [<startmodel>]{<startcolor>}.
}

\newcommand{\hgradrule@TP}[2][]% Pick up next pair of arguments: [<startmodel>]{<startcolor>}.
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{startcolor@TP}{#2}}
  {\definecolor{startcolor@TP}{#1}{#2}}%
  \@hgradrule@TP
}

\newcommand{\@hgradrule@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{endcolor@TP}{#2}}
  {\definecolor{endcolor@TP}{#1}{#2}}%
  \@@hgradrule@TP%                         Pick up rule arguments and proceed.
}

\newcommand{\vstripe@TP}[4]%              Helper command for making _one_ stripe. Can be overladed for making historams.
{{\setcolor@TP{stripecolor@TP}\rule{#2}{#3}#4}}

\newcommand{\@@hgradrule@TP}[3][0pt]%      Main part of \hgradrule.
{%
  \ifthenelse{\value{stripes@TP}<2}%       A `pathological case' which can happen in animations: If 0 or 1 stripes are
                                   %       requested, a division by zero error would be produced by the gradient code.
  {\mbox{{\setcolor@TP{startcolor@TP}\rule[#1]{#2}{#3}}}}% In this case, just produce a colored rule.
  {%
    \raisebox{#1}%                         Evaluate the <raise> argument of the rule.
    {%
      \setcounter{stripe@TP}{0}%           Initialize the number of the current stripe.
      \whiledo{\value{stripe@TP}<\value{stripes@TP}}
      {%
        \mkgradfirstfactor@TP{\tmp@TP}%    Make the weight for \colorbetween, based on the number of the current stripe
        {\value{stripe@TP}/(\value{stripes@TP}-1)}% and the first gradient progression.
        \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{startcolor@TP}% Calculate stripe color.
        \stepcounter{stripe@TP}%
        \ifthenelse{\value{stripe@TP}=\value{stripes@TP}}%     Last stripe?
        {\vstripe@TP{\tmp@TP}{(#2)/\value{stripes@TP}}{#3}{}}% Yes; make stripe w/o overlap.
        {%                                                     No; add a kern to make stripes overlap.
          \vstripe@TP{\tmp@TP}{(#2)/\value{stripes@TP}+\stripeoverlap}{#3}{\kern-\stripeoverlap}%
          }%
        }% matches \whiledo{\value{stripe@TP}<\value{stripes@TP}}{%
      }% matches \raisebox{#1}{%
    }% matches second argument of \ifthenelse{\value{stripes@TP}<2}%
  }% matches \newcommand{\@@hgradrule@TP}[3][0pt]{%


% \dblhgradrule[<midpoint>][<stripes>]
% [<startmodel>]{<startcolor>}[<midmodel>]{<midcolor>}[<endmodel>]{<endcolor>}
% [<raise>]{<width>}{<height>}
% creates a rule-like object consisting of a horizontal color gradient composed of vertical stripes.
% 
% Parameters are exactly as those for \dblvgradrule (replacing `top' by `left' and `bottom' by `right'). See there for
% explanations. 
%
\newcommand{\dblhgradrule}[1][]% Pick up first optional argument: [<midpoint>].
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameters for rules.
  \let\secondgradprogression@TP=\rulesecondgradprogression
  \ifthenelse{\equal{#1}{}}{\let\gradmidpoint@TP=\rulegradmidpoint}{\def\gradmidpoint@TP{#1}}%
  \dblhgradrule@TP
}

\newcommand{\dblhgradrule@TP}[1][]% Pick up second optional argument: [<stripes>].
{%
  \ifthenelse{\equal{#1}{}}{\setcounter{stripes@TP}{\rulestripes}}{\setcounter{stripes@TP}{#1}}%
  \@dblhgradrule@TP
}

\newcommand{\@dblhgradrule@TP}[2][]% Pick up next pair of arguments: [<startmodel>]{<startcolor>}.
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@@dblhgradrule@TP
}

\newcommand{\@@dblhgradrule@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{midcolor@TP}{#2}}{\definecolor{midcolor@TP}{#1}{#2}}%
  \@@@dblhgradrule@TP
}

\newcommand{\@@@dblhgradrule@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}
  {\replacecolor{endcolor@TP}{#2}}
  {\definecolor{endcolor@TP}{#1}{#2}}%
  \@@@@dblhgradrule@TP%                         Pick up rule arguments and proceed.
}

\newcommand{\@@@@dblhgradrule@TP}[3][0pt]%             Main part of \dblhgradrule.
{%
  \ifthenelse{\value{stripes@TP}<2}%                   The gradient code is not equipped for making less than 2 stripes.
  {\mbox{{\setcolor@TP{midcolor@TP}\rule[#1]{#2}{#3}}}}% In this case, just produce a rule colored with the middle color.
  {%
    \raisebox{#1}%                                     Evaluate the <raise> argument of the rule.
    {%
      \setcounter{stripe@TP}{0}%                       Initialize the number of the current stripe.
      \setcounter{tmpcnta@TP}%                          Number of the `middle' stripe.
      {\value{stripes@TP}*\real{\gradmidpoint@TP}}%
      \whiledo{\value{stripe@TP}<\value{tmpcnta@TP}}%   Produce the left part of the gradient.
      {%
        \mkgradfirstfactor@TP{\tmp@TP}%                 Make the weight for \colorbetween, based on the number of the 
        {\value{stripe@TP}/\value{tmpcnta@TP}}%         current stripe and the first gradient progression.
        \colorbetween[\tmp@TP]{stripecolor@TP}{midcolor@TP}{startcolor@TP}% Calculate stripe color.
        \vstripe@TP{\tmp@TP}%                                               Make stripe with overlap.
        {(#2)/\value{stripes@TP}+\stripeoverlap}{#3}{\kern-\stripeoverlap}% This is the left part, remember?
        \stepcounter{stripe@TP}%
        }%
      \stepcounter{tmpcnta@TP}%
      \ifthenelse{\value{stripes@TP}=\value{tmpcnta@TP}}% Only one stripe left to produce?
      {\vstripe@TP{1}{(#2)/\value{stripes@TP}}{#3}{}}%    Just produce one stripe colored with the end color.
      {%
        \whiledo{\value{stripe@TP}<\value{stripes@TP}}%   Produce the right part of the gradient.
        {%
          \mkgradsecondfactor@TP{\tmp@TP}%                Make the weight for \colorbetween.
          {(\value{stripe@TP}-\value{tmpcnta@TP})/(\value{stripes@TP}-\value{tmpcnta@TP}-1)}%
          \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{midcolor@TP}% Calculate stripe color.
          \stepcounter{stripe@TP}%
          \ifthenelse{\value{stripe@TP}=\value{stripes@TP}}%     Last stripe?
          {\vstripe@TP{\tmp@TP}{(#2)/\value{stripes@TP}}{#3}{}}% Yes; make stripe w/o overlap.
          {%                                                     Add kern to make stripes overlap.
            \vstripe@TP{\tmp@TP}{(#2)/\value{stripes@TP}+\stripeoverlap}{#3}{\kern-\stripeoverlap}%
            }%
          }% matches \whiledo{\value{stripe@TP}<\value{stripes@TP}}{%
        }% matches second argument of \ifthenelse{\value{stripes@TP}=\value{tmpcnta@TP}}%
      }% matches \raisebox{#1}{%
    }% matches second argument of \ifthenelse{\value{stripes@TP}<2}%
  }% matches \newcommand{\@@@@dblhgradrule@TP}[3][0pt]{% 


%=======================================================================================================================
%===========================================RESTRICTED AREA!============================================================
%vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

% PDF:
% \def\clipbox{\@ifnextchar[{\clipbox@}{\clipbox@[0pt]}}
% \def\clipbox@[#1]#2{%
%   \begingroup
%     \setlength{\@tempdima}{#1}%
%     \setbox\@tempboxa=\hbox{%
%       \color@begingroup
%       #2%
%       \color@endgroup
%     }%
%     \leavevmode\hbox to \wd\@tempboxa{%
%       \@ifundefined{dimexpr}{%
%         \@defbp\x{-\@tempdima}%
%         \@tempdimc=\dp\@tempboxa
%         \advance\@tempdimc by \@tempdima
%         \@defbp\y{-\@tempdimc}%
%         \@tempdimc=\wd\@tempboxa
%         \advance\@tempdimc by 2\@tempdima
%         \@defbp\w{\@tempdimc}%
%         \@tempdimc=\dp\@tempboxa
%         \advance\@tempdimc by \ht\@tempboxa
%         \advance\@tempdimc by 2\@tempdima
%         \@defbp\h{\@tempdimc}%
%         \pdfliteral{%
%           q % gsave
%           \x\space\y\space\w\space\h\space re % rectangle
%           W n% make clip-path
%         }%
%       }{% e-TeX
%          \pdfliteral{%
%           q % gsave
%           \@dimtobp{-\@tempdima} % x
%           \@dimtobp{-\dp\@tempboxa-\@tempdima} % y
%           \@dimtobp{\wd\@tempboxa+2\@tempdima} % width
%           \@dimtobp{\dp\@tempboxa+\ht\@tempboxa+2\@tempdima} % height
%           re % rectangle
%           W n% make clip-path
%         }%
%       }%
%       \rlap{\unhbox\@tempboxa}%
%       \pdfliteral{%
%         Q% grestore
%       }%
%       \hss
%     }%
%   \endgroup
% }
% \begingroup\expandafter\expandafter\expandafter\endgroup
% \expandafter\ifx\csname dimexpr\endcsname\relax
%   \def\@defbp#1#2{%
%     \setlength{\@tempdimb}{#2}%
%     \setlength{\@tempdimb}{.99626401\@tempdimb}%
%     \edef#1{\strip@pt\@tempdimb}%
%   }
% \else
%   \def\@dimtobp#1{%
%     \strip@pt\dimexpr.99626401\dimexpr#1\relax\relax
%   }
% \fi
%
% PS: 
% \def\clipbox{\@ifnextchar[{\clipbox@}{\clipbox@[0pt]}}
% \def\clipbox@[#1]#2{%
%   \begingroup
%     \setlength{\@tempdima}{#1}%
%     \setbox\@tempboxa=\hbox{%
%       \color@begingroup
%       #2%
%       \color@endgroup
%     }%
%     \leavevmode\hbox to \wd\@tempboxa{%
%       \@ifundefined{dimexpr}{%  
%         \@defpt\x{-\@tempdima}% 
%         \@tempdimc=\ht\@tempboxa
%         \advance\@tempdimc by \@tempdima
%         \@defpt\y{-\@tempdimc}% 
%         \@tempdimc=\wd\@tempboxa
%         \advance\@tempdimc by 2\@tempdima
%         \@defpt\w{\@tempdimc}%  
%         \@tempdimc=\dp\@tempboxa
%         \advance\@tempdimc by \ht\@tempboxa
%         \advance\@tempdimc by 2\@tempdima
%         \@defpt\h{\@tempdimc}%
%         \special{ps:%
%           gsave %
%           SDict begin %
%           \x\space PTtoDVIPS \y\space PTtoDVIPS rmoveto %
%           currentpoint %
%           \w\space PTtoDVIPS \h\space PTtoDVIPS rectclip %
%           end%
%         }%
%       }{% e-TeX
%          \special{ps:%
%           gsave %
%           SDict begin %
%           \@dimtopt{-\@tempdima} PTtoDVIPS % x
%           \@dimtopt{-\ht\@tempboxa-\@tempdima} PTtoDVIPS % y
%           rmoveto currentpoint %
%           \@dimtopt{\wd\@tempboxa+2\@tempdima} PTtoDVIPS % width
%           \@dimtopt{\dp\@tempboxa+\ht\@tempboxa+2\@tempdima} %
%           PTtoDVIPS % height
%           rectclip %
%           end%
%         }%
%       }%
%       \rlap{\unhbox\@tempboxa}%
%       \special{ps:grestore}%
%       \hss
%     }%
%   \endgroup
% }
% \special{!%
%   /PTtoDVIPS{72.27 div Resolution mul}def%
%   % rectclip is a level 2 feature
%   /rectclip where{pop}{%
%     /rectclip{%
%       newpath %
%       4 2 roll moveto %
%       exch dup 0 rlineto %
%       exch 0 exch rlineto %
%       neg 0 rlineto %
%       closepath %
%       clip %
%       newpath %
%     }bind def% 
%   }%
%   ifelse%
% }
% \begingroup\expandafter\expandafter\expandafter\endgroup
% \expandafter\ifx\csname dimexpr\endcsname\relax
%   \def\@defpt#1#2{%
%     \setlength{\@tempdimb}{#2}%
%     \edef#1{\strip@pt\@tempdimb}%
%   }
% \else
%   \def\@dimtopt#1{%
%     \strip@pt\dimexpr#1\relax
%   }
% \fi


\ifpdf
  \newcommand{\clipbox}[2][\z@]
  {%
    \setlength{\@tempdima}{#1}%
    \setbox\@tempboxa=
    \hbox{\kern\@tempdima\vbox{\offinterlineskip\kern\@tempdima\hbox{#2}\kern\@tempdima}\kern\@tempdima}%
    \pdfxform\@tempboxa
    \leavevmode
    \hbox
    {%
      \kern-\@tempdima
      \vbox{\offinterlineskip\kern-\@tempdima\hbox{\pdfrefxform\pdflastxform}\kern-\@tempdima}%
      \kern-\@tempdima
      }%
    }
 \else
  \providecommand{\clipbox}[2][\z@]{\leavevmode\hbox{#2}}
\fi

\newcommand{\dgradslope}{1,1}

\newcounter{dgradhslope@TP}

\newcounter{dgradvslope@TP}

\def\setdgradslope(#1,#2){\setcounter{dgradhslope@TP}{#1}\setcounter{dgradvslope@TP}{#2}}

\newcommand{\dgradrule}[1][]
{%
  \ifthenelse{\equal{#1}{}}{\expandafter\setdgradslope\expandafter(\dgradslope)}{\setdgradslope(#1)}%
  \dgradrule@TP
}

\newcommand{\dgradrule@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@dgradrule@TP
}

\newcommand{\@dgradrule@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{endcolor@TP}{#2}}{\definecolor{endcolor@TP}{#1}{#2}}%
  \@@dgradrule@TP
}

\newcommand{\dstripewd@TP}{.7pt}

\newcommand{\@@dgradrule@TP}[3][0pt]
{%
  \raisebox{#1}
  {%
    \thicklines
    \setcounter{stripe@TP}{0}%
    \setcounter{tmpcnta@TP}{1*\ratio{#3}{\dstripewd@TP}}%
    \setcounter{stripes@TP}{1*\ratio{#3}{\dstripewd@TP}+1*\ratio{#2}{\dstripewd@TP}}%
    \@xarg\c@dgradhslope@TP\@yarg\c@dgradvslope@TP
    \makebox[\dstripewd@TP]
    {%
      \whiledo{\value{stripe@TP}<\value{tmpcnta@TP}}
      {%
        \mkfactor{\tmp@TP}{\value{stripe@TP}/(\value{stripes@TP}-1)}%
        \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{startcolor@TP}%
        \setlength{\@linelen}{\dstripewd@TP*\value{stripe@TP}}%
        \raisebox{\dstripewd@TP*(\value{tmpcnta@TP}-\value{stripe@TP})}
        {\makebox[0pt]{{\setcolor@TP{stripecolor@TP}\hbox to 0pt{\@sline\hss}}}}%
        \stepcounter{stripe@TP}%
        }%
      }%
    \whiledo{\value{stripe@TP}<\value{stripes@TP}}
    {%
      \mkfactor{\tmp@TP}{\value{stripe@TP}/(\value{stripes@TP}-1)}%
      \colorbetween[\tmp@TP]{stripecolor@TP}{endcolor@TP}{startcolor@TP}%
      \makebox[\dstripewd@TP]{{\setcolor@TP{stripecolor@TP}.}}%
      \stepcounter{stripe@TP}%
      }%
    }%
  }%

%^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
%===========================================RESTRICTED AREA!============================================================
%=======================================================================================================================


%-----------------------------------------------------------------------------------------------------------------------
% Structured box backgrounds.

% \vgradbox[<stripes>][<startmodel>]{<startcolor>}[<endmodel>]{<endcolor>}{<content>} creates an mbox containing
% <content>, which has a background made up of a vertical color gradient. In fact, the background exceeds the extent of
% <content> by the value of \fboxsep on every side, just like the \colorbox command from the color package. 
%
% The gradient background is constructed using the \vgradrule command; see the description of \vgradrule on the way the
% gradient is constructed and on the meaning of the parameters <stripes>, <startmodel>, <startcolor>, <endmodel>,
% <endcolor> and the additional parameter \rulefirstgradprogression which has the same meaning for \vgradbox as for
% \vgradrule. 
% 
\newcommand{\vgradbox}[1][]% Pick up first optional argument: [<stripes>].
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameter for rules.
  \ifthenelse{\equal{#1}{}}%                               First optional argument given?
  {\setcounter{stripes@TP}{\rulestripes}}%                 No; use default value.
  {\setcounter{stripes@TP}{#1}}%                           Yes.
  \vgradbox@TP%                                            Pick up remaining optional arguments.
}

\newcommand{\vgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@vgradbox@TP
}

\newcommand{\@vgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{endcolor@TP}{#2}}{\definecolor{endcolor@TP}{#1}{#2}}%
  \@@gradbox@TP\@@vgradrule@TP%                    Make a generic background box with vertical gradient background.
}

\newcommand{\@@gradbox@TP}[2]%                     Generic background box.
{%
  \leavevmode%                                     Make box behave like \mbox.
  \setbox\tempbox@TP
  \hbox{\kern\fboxsep{\set@color#2}\kern\fboxsep}% An \hbox containing <contents> plus additional white space.
  \rlap%                                           Underlay box background with rule command passed as #1.
  {%
    #1[-\fboxsep-\dp\tempbox@TP]%                  Box depth augmented by `white' space.
    {\wd\tempbox@TP}%                              Space on the sides has already been added.
    {\ht\tempbox@TP+\dp\tempbox@TP+2\fboxsep}}%    Total height.
  \box\tempbox@TP%                                 Overlay box contents.
  }%

% \hgradbox[<stripes>][<startmodel>]{<startcolor>}[<endmodel>]{<endcolor>}{<content>} acts like \vgradbox, but creates
% the background using \hgradrule. See comments above.
% 
\newcommand{\hgradbox}[1][]
{%
  \let\secondgradprogression@TP=\rulesecondgradprogression
  \ifthenelse{\equal{#1}{}}{\setcounter{stripes@TP}{\rulestripes}}{\setcounter{stripes@TP}{#1}}%
  \hgradbox@TP
}

\newcommand{\hgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@hgradbox@TP
}

\newcommand{\@hgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{endcolor@TP}{#2}}{\definecolor{endcolor@TP}{#1}{#2}}%
  \@@gradbox@TP\@@hgradrule@TP
}


% \dblvgradbox[<midpoint>][<stripes>][<startmodel>]{<startcolor>}[<midmodel>]{<midcolor>}[<endmodel>]{<endcolor>}
% {<contents>} 
% acts like \vgradbox, but creates the background using \dblvgradrule (hence the additional parameters). See comments
% above (and the description of \dblvgradrule concerning the meaning of \dblvgradrule parameters). 
% 
\newcommand{\dblvgradbox}[1][]
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression%  Use progression parameters for rules.
  \let\secondgradprogression@TP=\rulesecondgradprogression
  \ifthenelse{\equal{#1}{}}{\let\gradmidpoint@TP=\rulegradmidpoint}{\def\gradmidpoint@TP{#1}}%
  \dblvgradbox@TP
}

\newcommand{\dblvgradbox@TP}[1][]
{%
  \ifthenelse{\equal{#1}{}}{\setcounter{stripes@TP}{\rulestripes}}{\setcounter{stripes@TP}{#1}}%
  \@dblvgradbox@TP
}

\newcommand{\@dblvgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@@dblvgradbox@TP
}

\newcommand{\@@dblvgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{midcolor@TP}{#2}}{\definecolor{midcolor@TP}{#1}{#2}}%
  \@@@dblvgradbox@TP
}

\newcommand{\@@@dblvgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{endcolor@TP}{#2}}{\definecolor{endcolor@TP}{#1}{#2}}%
  \@@gradbox@TP\@@@@dblvgradrule@TP
}


% \dblhgradbox[<midpoint>][<stripes>][<startmodel>]{<startcolor>}[<midmodel>]{<midcolor>}[<endmodel>]{<endcolor>}
% {<contents>} 
% acts like \dblvgradbox, but creates the background using \dblhgradrule. See comments above. 
% 
\newcommand{\dblhgradbox}[1][]
{%
  \let\firstgradprogression@TP=\rulefirstgradprogression
  \let\secondgradprogression@TP=\rulesecondgradprogression
  \ifthenelse{\equal{#1}{}}{\let\gradmidpoint@TP=\rulegradmidpoint}{\def\gradmidpoint@TP{#1}}%
  \dblhgradbox@TP
}

\newcommand{\dblhgradbox@TP}[1][]
{%
  \ifthenelse{\equal{#1}{}}{\setcounter{stripes@TP}{\rulestripes}}{\setcounter{stripes@TP}{#1}}%
  \@dblhgradbox@TP
}

\newcommand{\@dblhgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{startcolor@TP}{#2}}{\definecolor{startcolor@TP}{#1}{#2}}%
  \@@dblhgradbox@TP
}

\newcommand{\@@dblhgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{midcolor@TP}{#2}}{\definecolor{midcolor@TP}{#1}{#2}}%
  \@@@dblhgradbox@TP
}

\newcommand{\@@@dblhgradbox@TP}[2][]
{%
  \ifthenelse{\equal{#1}{}}{\replacecolor{endcolor@TP}{#2}}{\definecolor{endcolor@TP}{#1}{#2}}%
  \@@gradbox@TP\@@@@dblhgradrule@TP
}


%-----------------------------------------------------------------------------------------------------------------------
% Structured page backgrounds.

% \backgroundstyle[<options>]{<style>} is the central command for structured page backgrounds. It works like \pagestyle
% and other commands of this type. This means <style> is a symbolic name specifying the general method by which the page
% background is constructed.
% The detailed construction is influenced by parameters which can be set in <options>. If given, the optional parameter
% <options> should contain a list of settings in ``keyval'' manner. The keyval method (which is used by the
% \includegraphics command from the graphicx package, for instance) is based on associating a symbolic name with every
% parameter. <options> is then a comma-separated list of parameter settings of the form <name>=<value>, where <name> is
% the symbolic name of the parameter to be set and <value> is the value it is to be set to.
% Not every <style> evaluates every parameter. In the following, a description of all styles, together with lists of the
% parameters employed, is given. It is followed by a list of all parameters.
% Note that some parameter names internally access the same parameter. For instance, parameters startcolor and
% startcolordef both set the start color of a color gradient. In case of conflict, the last setting in the list
% <options> will prevail. It is noted in the list of parameters which other parameters are overwritten. 
%
% <style> may have one of the following values:
%
% none  No background. This means the page background is whatever it would be if \backgroundstyle wasn't used at all
%       (for instance, a plain area of color pagecolor if one of the color options has been given).
%       Parameters used: none.
%
%       
% plain Plain background. This means the page background is whatever it would be if \backgroundstyle wasn't used at all
%       (for instance, a plain area of color pagecolor if one of the color options has been given). In addition to
%       background style ``none'', the background style ``plain'' does produce panel backgrounds. The colors and
%       dimensions of a ``top panel'', ``bottom panel'', ``left panel'', and ``right panel'' can be specified. 
%
%       Parameters used: hpanels, autopanels, toppanelcolor, bottompanelcolor, leftpanelcolor, rightpanelcolor, 
%                        toppanelcolordef, bottompanelcolordef, leftpanelcolordef, rightpanelcolordef, 
%                        toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.
%
%
% vgradient     Vertical gradient. The page background is constructed using the \vgradrule command.
%               In addition to the usual parameters of gradient rules, the vgradient background style allows to leave
%               space for headers, footers, or panels. The colors and dimensions of a ``top panel'', ``bottom panel'',
%               ``left panel'', and ``right panel'' can be specified. The gradient rule fills the rectangular space left
%               between the specified panels.
% 
%               Parameters used:        stripes, firstgradprogression, startcolor, startcolordef, endcolor, endcolordef,
%                                       hpanels, autopanels,
%                                       toppanelcolor, bottompanelcolor, leftpanelcolor, rightpanelcolor, 
%                                       toppanelcolordef, bottompanelcolordef, leftpanelcolordef, rightpanelcolordef, 
%                                       toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.
%
%                                       
% hgradient     Horizontal gradient. The page background is constructed using the \hgradrule command.
%               See the description of vgradient concerning panels.
% 
%               Parameters used:        stripes, firstgradprogression, startcolor, startcolordef, endcolor, endcolordef,
%                                       hpanels, autopanels,
%                                       toppanelcolor, bottompanelcolor, leftpanelcolor, rightpanelcolor, 
%                                       toppanelcolordef, bottompanelcolordef, leftpanelcolordef, rightpanelcolordef, 
%                                       toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.
%
% doublevgradient  `Double' vertical gradient. The page background is constructed using the \dblvgradrule command.
%                  See the description of vgradient concerning panels.
% 
%               Parameters used:        stripes, gradmidpoint, firstgradprogression, secondgradprogression,
%                                       startcolor, startcolordef, midcolor, midcolordef, endcolor, endcolordef,
%                                       hpanels, autopanels,
%                                       toppanelcolor, bottompanelcolor, leftpanelcolor, rightpanelcolor, 
%                                       toppanelcolordef, bottompanelcolordef, leftpanelcolordef, rightpanelcolordef, 
%                                       toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.
%
% doublehgradient  `Double' horizontal gradient. The page background is constructed using the \dblhgradrule command.
%                  See the description of vgradient concerning panels.
% 
%               Parameters used:        stripes, gradmidpoint, firstgradprogression, secondgradprogression,
%                                       startcolor, startcolordef, midcolor, midcolordef, endcolor, endcolordef,
%                                       hpanels, autopanels,
%                                       toppanelcolor, bottompanelcolor, leftpanelcolor, rightpanelcolor, 
%                                       toppanelcolordef, bottompanelcolordef, leftpanelcolordef, rightpanelcolordef, 
%                                       toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.
%
%
% Now, a list of all parameters and their meaning. In the following,
%
% <n>   denotes a (calc expression for a) nonnegative integer
% <i>   denotes a (calc expression for an) integer
% <r>   denotes a fixed-point number
% <l>   denotes a (calc expression for a) length
% <c>   denotes the name of a defined color
% <cm>  denotes a valid color model name (in the sense of the color package)
% <cd>  denotes a valid color definition (in the sense of the color package) wrt a given <cm> parameter
% <t>   denotes a `truth value' in the sense of the ifthen package: either true or false. As usual for keyval, if =<t>
%       is omitted, the default true is assumed.
%
% Parameter                     Meaning
%
% stripes=<n>                   Set the <stripes> parameter of gradient rules to <n>.
%                               Default: \bgndstripes
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%
% gradmidpoint=<r>              Set the <midpoint> parameter of double gradient rules to <r>.
%                               Default: \bgndgradmidpoint
%                               Used by: doublevgradient, doublehgradient
%
% firstgradprogression=<i>      Set the first gradient progression of gradient rules to <i>.
%                               Default: \bgndfirstgradprogression
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%
% secondgradprogression=<i>     Set the second gradient progression of double gradient rules to <i>.
%                               Default: \bgndsecondgradprogression
%                               Used by: doublevgradient, doublehgradient
%
% startcolor=<c>                Set the <startcolor> parameter of gradient rules to <c>.
%                               Default: If neither startcolor nor startcolordef is given, the color bgndstartcolor is
%                                        used as <startcolor>.
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: startcolordef
%
% startcolordef={<cm>}{<cd>}    Set the <startcolor> parameter of gradient rules to color foo, which is obtained by
%                               \definecolor{foo}{<cm>}{<cd>}. Note that the two pairs of curly braces are mandatory.
%                               Default: If neither startcolor nor startcolordef is given, the color bgndstartcolor is
%                                        used as <startcolor>.
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: startcolor
%
% endcolor=<c>                  Set the <endcolor> parameter of gradient rules to <c>.
%                               Default: If neither endcolor nor endcolordef is given, the color bgndendcolor is
%                                        used as <endcolor>.
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: endcolordef
%
% endcolordef={<cm>}{<cd>}      Set the <endcolor> parameter of gradient rules to color foo, which is obtained by
%                               \definecolor{foo}{<cm>}{<cd>}. Note that the two pairs of curly braces are mandatory.
%                               Default: If neither endcolor nor endcolordef is given, the color bgndendcolor is
%                                        used as <endcolor>.
%                               Used by: vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: endcolor
%
% midcolor=<c>                  Set the <midcolor> parameter of double gradient rules to <c>.
%                               Default: If neither midcolor nor midcolordef is given, the color bgndmidcolor is
%                                        used as <midcolor>.
%                               Used by: doublevgradient, doublehgradient
%                               Overwrites: midcolordef
%
% midcolordef={<cm>}{<cd>}      Set the <midcolor> parameter of double gradient rules to color foo, which is obtained by
%                               \definecolor{foo}{<cm>}{<cd>}. Note that the two pairs of curly braces are mandatory.
%                               Default: If neither midcolor nor midcolordef is given, the color bgndmidcolor is
%                                        used as <midcolor>.
%                               Used by: doublevgradient, doublehgradient
%                               Overwrites: midcolor
%
% hpanels=<t>                   Specifies the `direction' of panels produced. hpanels=true means the top and bottom
%                               panel span the full width of the screen. In the space left in the middle, the left
%                               panel, the background itself, and the right panel are displayed.
%                               hpanels=false means the left and right panel span the full height of the screen. In the
%                               space left in the middle, the top panel, the background itself, and the bottom panel are
%                               displayed. 
%                               Default: hpanels=true is the default for plain, hgradient and
%                                        doublehgradient. hpanels=false is the default for vgradient and
%                                        doublevgradient.
%                               Used by: plain, vgradient, hgradient, doublevgradient, doublehgradient
%                               
% autopanels=<t>                Specifies whether the default values of the parameters toppanelheight,
%                               bottompanelheight, leftpanelwidth, rightpanelwidth should be calculated automatically
%                               from the contents of declared panels. 
%                               The automatism used is analogous to that of \DeclarePanel*.
%                               Note that for panel arrangement, both the width and the height of all declared panels
%                               are overwritten. If you don't want this, calculate the panel parameters yourself and set
%                               autopanels=false. In this case, the current panel dimensions of declared panels are used
%                               as defaults for toppanelheight, bottompanelheight, leftpanelwidth, rightpanelwidth.  
%                               Default: true.
%                               Used by: plain, vgradient, hgradient, doublevgradient, doublehgradient
%                               
% toppanelheight=<l> 
% bottompanelheight=<l> 
% leftpanelwidth=<l> 
% rightpanelwidth=<l>           Set the height/width of the space left for the top/bottom/left/right panel to <l>.
%                               Note that the remaining dimensions of panels, for instance the width of the top panel,
%                               are always calculated automatically, depending on the setting of the hpanels parameter.
%                               Default: If a respective panel has been defined using \DeclarePanel, the default used
%                                        depends on the setting of the autopanels parameter. 
%                                        If autopanels=true, the correct dimension is calculated from the contents of
%                                        the panel. The respective one of \toppanelheight, \bottompanelheight,
%                                        \leftpanelwidth, \rightpanelwidth is overwritten with the result.
%                                        If autopanels=false, then the respective setting of \toppanelheight,
%                                        \bottompanelheight, \leftpanelwidth, \rightpanelwidth is taken as the default.
%                                        If a panel has not been declared, the appropriate one of \bgndtoppanelheight,
%                                        \bgndbottompanelheight, \bgndleftpanelwidth, \bgndrightpanelwidth is used as
%                                        default. 
%                               Used by: plain, vgradient, hgradient, doublevgradient, doublehgradient
%
% toppanelcolor=<c>
% bottompanelcolor=<c>
% leftpanelcolor=<c>
% rightpanelcolor=<c>           Set the color of the space left for the top/bottom/left/right panel to <c>.
%                               Default: The standard colors toppanelcolor, bottompanelcolor, leftpanelcolor,
%                                        rightpanelcolor are used as defaults.
%                               Used by: plain, vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: toppanelcolordef bottompanelcolordef leftpanelcolordef rightpanelcolordef 
%
% toppanelcolordef={<cm>}{<cd>}
% bottompanelcolordef={<cm>}{<cd>}
% leftpanelcolordef={<cm>}{<cd>}
% rightpanelcolordef={<cm>}{<cd>}
%                               Set the color of the space left for the top/bottom/left/right panel to color foo, which
%                               is obtained by \definecolor{foo}{<cm>}{<cd>}. Note that the two pairs of curly braces
%                               are mandatory.  
%                               Default: See the description of top/bottom/left/rightpanelcolor.
%                               Used by: plain, vgradient, hgradient, doublevgradient, doublehgradient
%                               Overwrites: toppanelcolor bottompanelcolor leftpanelcolor rightpanelcolor 
%
\newcommand{\backgroundstyle}[2][]
{%
  \replacecolor{startcolor@TP}{bgndstartcolor}%                           Initialize the internal counterparts 
  \replacecolor{midcolor@TP}{bgndmidcolor}%                               of parameters to their default values.
  \replacecolor{endcolor@TP}{bgndendcolor}%
  \replacecolor{bgndtoppanelcolor@TP}{toppanelcolor}%                     
  \replacecolor{bgndbottompanelcolor@TP}{bottompanelcolor}%                     
  \replacecolor{bgndleftpanelcolor@TP}{leftpanelcolor}%                     
  \replacecolor{bgndrightpanelcolor@TP}{rightpanelcolor}%                     
  \let\firstgradprogression@TP=\bgndfirstgradprogression
  \let\secondgradprogression@TP=\bgndsecondgradprogression%
  \setcounter{stripes@TP}{\bgndstripes}%
  \let\gradmidpoint@TP=\bgndgradmidpoint
  \let\bgndtoppanelheight@TP=\empty%                 The panel dimensions depend on other parameters. If they are not 
  \let\bgndbottompanelheight@TP=\empty%              set directly, defaults are calculated after setting keyval
  \let\bgndleftpanelwidth@TP=\empty%                 parameters.
  \let\bgndrightpanelwidth@TP=\empty
  \let\hpanelsvalue@TP=\empty
  \setboolean{autopanels@TP}{true}%
  \csname set#2bgnd@TP\endcsname{#1}%                Execute the style-specific command which defines the background box.
  }


% Background-specific default values.

% Default number of stripes for gradient page backgrounds.
\newcommand{\bgndstripes}{10}

% Default position of the `middle' color of a double gradient.
\newcommand{\bgndgradmidpoint}{.5}

% Default gradient progression for page backgrounds (single gradients or first part of double gradients).
\newcommand{\bgndfirstgradprogression}{1}

% Default gradient progression for page backgrounds (second part of double gradients).
\newcommand{\bgndsecondgradprogression}{1}

% Default height/width of the space left for the top/bottom/left/right panel, in case no panel in the respective
% position has been declared. Otherwise, the defaults are taken from \toppanelheight, \bottompanelheight,
% \leftpanelwidth, \rightpanelwidth or calculated automatically, depending on the setting of the autopanels parameter.
% Note that the remaining dimensions of panels, for instance the width of the top panel, are always calculated
% automatically, depending on the setting of the hpanels parameter.
\newcommand{\bgndtoppanelheight}{0pt}

\newcommand{\bgndbottompanelheight}{0pt}

\newcommand{\bgndleftpanelwidth}{0pt}

\newcommand{\bgndrightpanelwidth}{0pt}


% Internal names for parameter values.

\newcommand{\bgndtoppanelheight@TP}{0pt}

\newcommand{\bgndtoppanelwidth@TP}{0pt}

\newcommand{\bgndbottompanelheight@TP}{0pt}

\newcommand{\bgndbottompanelwidth@TP}{0pt}

\newcommand{\bgndleftpanelheight@TP}{0pt}

\newcommand{\bgndleftpanelwidth@TP}{0pt}

\newcommand{\bgndrightpanelheight@TP}{0pt}

\newcommand{\bgndrightpanelwidth@TP}{0pt}

\newboolean{hpanels@TP}

\newboolean{autopanels@TP}


% The following commands define the keys for setting the parameters using the keyval package.

\define@key{bgnd@TP}{stripes}{\setcounter{stripes@TP}{#1}}


\define@key{bgnd@TP}{startcolor}{\replacecolor{startcolor@TP}{#1}}

\define@key{bgnd@TP}{startcolordef}{\definecolor{startcolor@TP}#1}


\define@key{bgnd@TP}{midcolor}{\replacecolor{midcolor@TP}{#1}}

\define@key{bgnd@TP}{midcolordef}{\definecolor{midcolor@TP}#1}


\define@key{bgnd@TP}{endcolor}{\replacecolor{endcolor@TP}{#1}}

\define@key{bgnd@TP}{endcolordef}{\definecolor{endcolor@TP}#1}


\define@key{bgnd@TP}{gradmidpoint}{\edef\gradmidpoint@TP{#1}}


\define@key{bgnd@TP}{firstgradprogression}{\def\firstgradprogression@TP{#1}}

\define@key{bgnd@TP}{secondgradprogression}{\def\secondgradprogression@TP{#1}}


\define@key{bgnd@TP}{hpanels}[true]{\def\hpanelsvalue@TP{#1}}

\define@key{bgnd@TP}{autopanels}[true]{\setboolean{autopanels@TP}{#1}}


\define@key{bgnd@TP}{toppanelcolor}{\replacecolor{bgndtoppanelcolor@TP}{#1}}

\define@key{bgnd@TP}{toppanelcolordef}{\definecolor{bgndtoppanelcolor@TP}#1}


\define@key{bgnd@TP}{bottompanelcolor}{\replacecolor{bgndbottompanelcolor@TP}{#1}}

\define@key{bgnd@TP}{bottompanelcolordef}{\definecolor{bgndbottompanelcolor@TP}#1}


\define@key{bgnd@TP}{leftpanelcolor}{\replacecolor{bgndleftpanelcolor@TP}{#1}}

\define@key{bgnd@TP}{leftpanelcolordef}{\definecolor{bgndleftpanelcolor@TP}#1}


\define@key{bgnd@TP}{rightpanelcolor}{\replacecolor{bgndrightpanelcolor@TP}{#1}}

\define@key{bgnd@TP}{rightpanelcolordef}{\definecolor{bgndrightpanelcolor@TP}#1}


\define@key{bgnd@TP}{toppanelheight}{\mklength@TP{\bgndtoppanelheight@TP}{#1}}

\define@key{bgnd@TP}{bottompanelheight}{\mklength@TP{\bgndbottompanelheight@TP}{#1}}

\define@key{bgnd@TP}{leftpanelwidth}{\mklength@TP{\bgndleftpanelwidth@TP}{#1}}

\define@key{bgnd@TP}{rightpanelwidth}{\mklength@TP{\bgndrightpanelwidth@TP}{#1}}


% Implementation of \backgroundstyle.

% In this box, the constructed background is stored. This box is placed behind every page at \shipout time by the kernel
% (see below).
\newbox\bgndbox@TP
\setbox\bgndbox@TP\null% Default: Empty.

% \mkpanels@TP{<command}} adds the panels to the main page background. The main page background should be produced by the
% command <command>, which is given the width and height of the central area as arguments.
\newcommand{\mkpanels@TP}[1]%
{%
  \ifthenelse{\boolean{hpanels@TP}}%                                    `horizontal' panels?
  {% Yes. Vertically align top panel, center area with left and right panels, and bottom panel.
    \vbox%                                                              A vbox with \offinterlineskip allows to align the
    {%                                                                  horizontal panels with the `background center'.
      \offinterlineskip
      \ifthenelse{\lengthtest{\bgndtoppanelheight@TP=0pt}}%             Should top panel be created?
      {}% No.
      {%
        \hbox{{%
            \setcolor@TP{bgndtoppanelcolor@TP}%
            \rule{\bgndtoppanelwidth@TP}{\bgndtoppanelheight@TP}%       Make horizontal colored area.
            }}%
        }% 
      \hbox%                                                            Make `background center'.
      {%
        \ifthenelse{\lengthtest{\bgndleftpanelwidth@TP=0pt}}%           Should left panel be created?
        {}% No.
        {{%                                                             
            \setcolor@TP{bgndleftpanelcolor@TP}%
            \rule{\bgndleftpanelwidth@TP}{\bgndleftpanelheight@TP}%     Make vertical colored area.
            }}%                                   
        #1%                                                             Make main background object.
        {\bgndtoppanelwidth@TP-\bgndleftpanelwidth@TP-\bgndrightpanelwidth@TP}% Calculate remaining space in the center.
        {\bgndleftpanelheight@TP}%
        \ifthenelse{\lengthtest{\bgndrightpanelwidth@TP=0pt}}%          Should right panel be created?
        {}% No.
        {{%                                                            
            \setcolor@TP{bgndrightpanelcolor@TP}%
            \rule{\bgndrightpanelwidth@TP}{\bgndrightpanelheight@TP}%   Make vertical colored area.
            }}%                                                         
        }% matches \hbox{%
      \ifthenelse{\lengthtest{\bgndbottompanelheight@TP=0pt}}%          Should bottom panel be created?
      {}% No.
      {%
        \hbox
        {{%
            \setcolor@TP{bgndbottompanelcolor@TP}%
            \rule{\bgndbottompanelwidth@TP}{\bgndbottompanelheight@TP}% Make horizontal colored area.
            }}%
        }%
      }% matches \vbox{%
    }% matches \ifthenelse{\boolean{hpanels@TP}}{%
  {% No. Horizontally align left panel, center area with top and bottom panels, and right panel.
    \ifthenelse{\lengthtest{\bgndleftpanelwidth@TP=0pt}}%               Should left panel be created?
    {}% No.
    {{%
        \setcolor@TP{bgndleftpanelcolor@TP}%
        \rule{\bgndleftpanelwidth@TP}{\bgndleftpanelheight@TP}%         Make vertical colored area.
        }}%
    \vbox%                                                              A vbox with \offinterlineskip allows to align
    {%                                                                  the horizontal panels with the center object.
      \offinterlineskip
      \ifthenelse{\lengthtest{\bgndtoppanelheight@TP=0pt}}%             Should top panel be created?
      {}% No.
      {%
        \hbox%                                                          
        {{%
            \setcolor@TP{bgndtoppanelcolor@TP}%
            \rule{\bgndtoppanelwidth@TP}{\bgndtoppanelheight@TP}%       Make horizontal colored area.
            }}%
        }%
      \hbox%                                                            Make main background object.
      {%
        #1%
        {\bgndtoppanelwidth@TP}%        
        {\bgndleftpanelheight@TP-\bgndtoppanelheight@TP-\bgndbottompanelheight@TP}% Calculate space in the center.
        }%
      \ifthenelse{\lengthtest{\bgndbottompanelheight@TP=0pt}}%          Should bottom panel be created?
      {}% No.
      {%
        \hbox%                                                          
        {{%
            \setcolor@TP{bgndbottompanelcolor@TP}%
            \rule{\bgndbottompanelwidth@TP}{\bgndbottompanelheight@TP}% Make horizontal colored area.   
            }}%
        }%
      }% matches \vbox{%
    \ifthenelse{\lengthtest{\bgndrightpanelwidth@TP=0pt}}%              Should right panel be created?
    {}% No.
    {{%
        \setcolor@TP{bgndrightpanelcolor@TP}%
        \rule{\bgndrightpanelwidth@TP}{\bgndrightpanelheight@TP}% Make vertical colored area.
        }}%
    }% matches second argument of \ifthenelse{\boolean{hpanels@TP}}
  }% matches \newcommand{\mkpanels@TP}[1]{%


% For those background styles which use panels, \initpanels@TP{<hpanels>} sets all panel-related parameters depending on
% the options and defaults. <hpanels> gives the background style dependent default of the hpanels option.
\newcommand{\initpanels@TP}[1]%
{%
  \ifx\hpanelsvalue@TP\empty%                          Has the hpanels parameter been given?
    \setboolean{hpanels@TP}{#1}%                       No; use default.
   \else
    \setboolean{hpanels@TP}{\hpanelsvalue@TP}%         Yes; use parameter setting.
  \fi
  \ifthenelse{\boolean{hpanels@TP}}%                   `horizontal' panel direction?
  {% Yes. Horizontal panels are `outer', vertical panels are `inner'.
    \let\bgndtoppanelwidth@TP=\TPpagewidth%            Full width for horizontal panels.
    \let\bgndbottompanelwidth@TP=\TPpagewidth%
    \ifthenelse{\equal{\bgndtoppanelheight@TP}{}}%     Has the top panel height been set?
    {% No. Guess default.
      \ifx\toppanelcontents@TP\empty%                  Is the panel defined?
        \mklength@TP{\bgndtoppanelheight@TP}{\bgndtoppanelheight}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%          Calculate panel dimensions?
        {% Yes.
          \calcvdimen@TP{\bgndtoppanelheight@TP}{\bgndtoppanelwidth@TP}% Measure the height of panel contents.
          {\toppanelcontents@TP}% 
          \let\toppanelheight=\bgndtoppanelheight@TP%  Overwrite panel settings.
          \let\toppanelwidth=\bgndtoppanelwidth@TP%
          \def\toppanelshift{0pt}%                     Top panel spans the whole upper screen.
          }
        {% No
          \mklength@TP{\bgndtoppanelheight@TP}{\toppanelheight}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndtoppanelheight@TP}{}}
    {}% Yes. Nothing to do.
    \ifthenelse{\equal{\bgndbottompanelheight@TP}{}}%         Has the bottom panel height been set?
    {% No. Guess default.
      \ifx\bottompanelcontents@TP\empty%                      Is the bottom panel defined?
        \mklength@TP{\bgndbottompanelheight@TP}{\bgndbottompanelheight}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%                 Calculate panel dimensions?
        {% Yes.
          \calcvdimen@TP{\bgndbottompanelheight@TP}{\bgndbottompanelwidth@TP}% Measure the height of panel contents.
          {\bottompanelcontents@TP}% 
          \let\bottompanelheight=\bgndbottompanelheight@TP%   Overwrite panel settings.
          \let\bottompanelwidth=\bgndbottompanelwidth@TP%
          \def\bottompanelshift{0pt}%                         Bottom panel spans the whole upper screen.
          }
        {% No
          \mklength@TP{\bgndbottompanelheight@TP}{\bottompanelheight}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndbottompanelheight@TP}{}}
    {}% Yes. Nothing to do.
    \mklength@TP{\bgndleftpanelheight@TP}%                Calculate remaining space in the center.
    {\TPpageheight-\bgndtoppanelheight@TP-\bgndbottompanelheight@TP}%
    \let\bgndrightpanelheight@TP=\bgndleftpanelheight@TP% Height of left and right panels is equal.
    \ifthenelse{\equal{\bgndleftpanelwidth@TP}{}}%        Has the left panel width been set?
    {% No. Guess default.
      \ifx\leftpanelcontents@TP\empty%                    Is the panel defined?
        \mklength@TP{\bgndleftpanelwidth@TP}{\bgndleftpanelwidth}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%             Calculate panel dimensions?
        {% Yes.
          \calchdimen@TP{\bgndleftpanelwidth@TP}{\bgndleftpanelheight@TP}% Measure the `optimal' width of panel contents.
          {\leftpanelcontents@TP}% 
          \let\leftpanelheight=\bgndleftpanelheight@TP%   Overwrite panel settings.
          \let\leftpanelwidth=\bgndleftpanelwidth@TP%
          \let\leftpanelraise=\bgndbottompanelheight@TP%  Left panel is raised above bottom panel.
          }
        {% No
          \mklength@TP{\bgndleftpanelwidth@TP}{\leftpanelwidth}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndleftpanelwidth@TP}{}}
    {}% Yes. Nothing to do.
    \ifthenelse{\equal{\bgndrightpanelwidth@TP}{}}%       Has the right panel width been set?
    {% No. Guess default.
      \ifx\rightpanelcontents@TP\empty%                   Is the panel defined?
        \mklength@TP{\bgndrightpanelwidth@TP}{\bgndrightpanelwidth}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%             Calculate panel dimensions?
        {% Yes.
          \calchdimen@TP{\bgndrightpanelwidth@TP}{\bgndrightpanelheight@TP}% Measure `optimal' width of panel contents.
          {\rightpanelcontents@TP}% 
          \let\rightpanelheight=\bgndrightpanelheight@TP% Overwrite panel settings.
          \let\rightpanelwidth=\bgndrightpanelwidth@TP%
          \let\rightpanelraise=\bgndbottompanelheight@TP% Right panel is raised above bottom panel.
          }
        {% No
          \mklength@TP{\bgndrightpanelwidth@TP}{\rightpanelwidth}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndrightpanelwidth@TP}{}}
    {}% Yes. Nothing to do.
    }% matches \ifthenelse{\boolean{hpanels@TP}}
  {% No. Vertical panels are `outer', horizontal panels are `inner'.
    \let\bgndleftpanelheight@TP=\TPpageheight%          Full height for vertical panels.
    \let\bgndrightpanelheight@TP=\TPpageheight%
    \ifthenelse{\equal{\bgndleftpanelwidth@TP}{}}%      Has the left panel width been set?
    {% No. Guess default.
      \ifx\leftpanelcontents@TP\empty%                  Is the panel defined?
        \mklength@TP{\bgndleftpanelwidth@TP}{\bgndleftpanelwidth}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%           Calculate panel dimensions?
        {% Yes.
          \calchdimen@TP{\bgndleftpanelwidth@TP}{\bgndleftpanelheight@TP}% Measure the `optimal' width of panel contents.
          {\leftpanelcontents@TP}% 
          \let\leftpanelheight=\bgndleftpanelheight@TP% Overwrite panel settings.
          \let\leftpanelwidth=\bgndleftpanelwidth@TP%
          \def\leftpanelraise{0pt}%                     Left panel spans the whole left part of the screen.
          }
        {% No
          \mklength@TP{\bgndleftpanelwidth@TP}{\leftpanelwidth}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndleftpanelwidth@TP}{}}
    {}% Yes. Nothing to do.
    \ifthenelse{\equal{\bgndrightpanelwidth@TP}{}}%       Has the right panel width been set?
    {% No. Guess default.
      \ifx\rightpanelcontents@TP\empty%                   Is the panel defined?
        \mklength@TP{\bgndrightpanelwidth@TP}{\bgndrightpanelwidth}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%             Calculate panel dimensions?
        {% Yes.
          \calchdimen@TP{\bgndrightpanelwidth@TP}{\bgndrightpanelheight@TP}% Measure `optimal' width of panel contents.
          {\rightpanelcontents@TP}% 
          \let\rightpanelheight=\bgndrightpanelheight@TP% Overwrite panel settings.
          \let\rightpanelwidth=\bgndrightpanelwidth@TP%
          \def\rightpanelraise{0pt}%                      Right panel spans the whole left part of the screen.
          }
        {% No
          \mklength@TP{\bgndrightpanelwidth@TP}{\rightpanelwidth}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndrightpanelwidth@TP}{}}
    {}% Yes. Nothing to do.
    \mklength@TP{\bgndtoppanelwidth@TP}%                Calculate remaining space in the center.
    {\TPpagewidth-\bgndleftpanelwidth@TP-\bgndrightpanelwidth@TP}%
    \let\bgndbottompanelwidth@TP=\bgndtoppanelwidth@TP% Width of top and bottom panels is equal.
    \ifthenelse{\equal{\bgndtoppanelheight@TP}{}}%      Has the top panel height been set?
    {% No. Guess default.
      \ifx\toppanelcontents@TP\empty%                   Is the panel defined?
        \mklength@TP{\bgndtoppanelheight@TP}{\bgndtoppanelheight}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%           Calculate panel dimensions?
        {% Yes.
          \calcvdimen@TP{\bgndtoppanelheight@TP}{\bgndtoppanelwidth@TP}% Measure the height of panel contents.
          {\toppanelcontents@TP}% 
          \let\toppanelheight=\bgndtoppanelheight@TP%   Overwrite panel settings.
          \let\toppanelwidth=\bgndtoppanelwidth@TP%
          \let\toppanelshift=\bgndleftpanelwidth@TP%    Shift top panel to the right of left panel.
          }
        {% No
          \mklength@TP{\bgndtoppanelheight@TP}{\toppanelheight}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndtoppanelheight@TP}{}}
    {}% Yes. Nothing to do.
    \ifthenelse{\equal{\bgndbottompanelheight@TP}{}}%       Has the bottom panel height been set?
    {% No. Guess default.
      \ifx\bottompanelcontents@TP\empty%                    Is the panel defined?
        \mklength@TP{\bgndbottompanelheight@TP}{\bgndbottompanelheight}% Use background-specific default.
       \else
        \ifthenelse{\boolean{autopanels@TP}}%               Calculate panel dimensions?
        {% Yes.
          \calcvdimen@TP{\bgndbottompanelheight@TP}{\bgndbottompanelwidth@TP}% Measure the height of panel contents.
          {\bottompanelcontents@TP}% 
          \let\bottompanelheight=\bgndbottompanelheight@TP% Overwrite panel settings.
          \let\bottompanelwidth=\bgndbottompanelwidth@TP%
          \let\bottompanelshift=\bgndleftpanelwidth@TP%     Shift bottom panel to the right of left panel.
          }
        {% No
          \mklength@TP{\bgndbottompanelheight@TP}{\bottompanelheight}%   Use panel-specific default.
          }%
      \fi
      }% matches \ifthenelse{\equal{\bgndbottompanelheight@TP}{}}
    {}% Yes. Nothing to do.
    }% matches second argument of \ifthenelse{\boolean{hpanels@TP}}
  }% matches \newcommand{\initpanels@TP}[1]{


% Make an `invisible' rule.
\newcommand{\phantomrule@TP}[2]{\rule{0pt}{#2}\rule{#1}{0pt}}

% Implementations of individual background styles.

\newcommand{\setnonebgnd@TP}[1]%              Implementation of the background style ``none''.
{\global\setbox\bgndbox@TP=\null}%            Just produce an empty box.


\newcommand{\setplainbgnd@TP}[1]%             Implementation of the background style ``plain''.
{%
  \setkeys{bgnd@TP}{#1}%                      Evaluate parameters.
  \initpanels@TP{true}%                       Initialize panel parameters.
  \global\setbox\bgndbox@TP=\hbox{\mkpanels@TP{\phantomrule@TP}}% Make panels only.
  }% 


\newcommand{\setvgradientbgnd@TP}[1]%         Implementation of the background style ``vgradient''.
{%
  \setkeys{bgnd@TP}{#1}%                      Evaluate parameters.
  \initpanels@TP{false}%                      Initialize panel parameters.
  \global\setbox\bgndbox@TP=\hbox{\mkpanels@TP{\@@vgradrule@TP}}% Make background box.
  }

\newcommand{\sethgradientbgnd@TP}[1]%         Implementation of the background style ``hgradient''.
{%
  \setkeys{bgnd@TP}{#1}%                      Evaluate parameters.
  \initpanels@TP{true}%                       Initialize panel parameters.
  \global\setbox\bgndbox@TP=\hbox{\mkpanels@TP{\@@hgradrule@TP}}% Make background box.
  }


\newcommand{\setdoublevgradientbgnd@TP}[1]%   Implementation of the background style ``doublevgradient''.
{%
  \setkeys{bgnd@TP}{#1}%                      Evaluate parameters.
  \initpanels@TP{false}%                      Initialize panel parameters.
  \global\setbox\bgndbox@TP=\hbox{\mkpanels@TP{\@@@@dblvgradrule@TP}}% Make background box.
  }


\newcommand{\setdoublehgradientbgnd@TP}[1]%   Implementation of the background style ``doublehgradient''.
{%
  \setkeys{bgnd@TP}{#1}%                      Evaluate parameters.
  \initpanels@TP{true}%                       Initialize panel parameters.
  \global\setbox\bgndbox@TP=\hbox{\mkpanels@TP{\@@@@dblhgradrule@TP}}% Make background box.
  }


% \hpagecolor[<start>]{<end>} is provided here for compatibility with background.sty from PPower4. It sets a horizontal
% gradient background. See the PPower4 documentation on the meaning of the arguments (which is quite confusing).
\providecommand{\hpagecolor}[2][]
{%
  \ifthenelse{\equal{#1}{}}
  {\colorbetween{ppendcolor}{#2}{white}\backgroundstyle[startcolor=#2,endcolor=ppendcolor]{hgradient}}
  {\backgroundstyle[startcolor=#1,endcolor=#2]{hgradient}}%
  }

% \vpagecolor[<start>]{<end>} is provided here for compatibility with background.sty from PPower4. It sets a vertical
% gradient background.  See the PPower4 documentation on the meaning of the arguments (which is quite confusing).
\providecommand{\vpagecolor}[2][]
{%
  \ifthenelse{\equal{#1}{}}
  {\colorbetween{ppendcolor}{#2}{white}\backgroundstyle[startcolor=#2,endcolor=ppendcolor]{vgradient}}
  {\backgroundstyle[startcolor=#1,endcolor=#2]{vgradient}}%
  }


%=======================================================================================================================
% Panels.
%
% The following code is rather preliminary and provides only the very basics for constructing panels. If you're using a
% document class or package which allows to do this or know how to achieve it using fancy headers, don't even consider
% using the following.


%-----------------------------------------------------------------------------------------------------------------------
% Some configurable panel parameters.

% Margin around panels (space [on all sides] between beginning of background and panel contents).
\mklength@TP{\panelmargin}{\fboxsep}

% Dimensions of top panel. Note that parts or all of these dimensions might be overwritten by \DeclarePanel* or
% using \backgroundstyle with specific settings.
\newcommand{\toppanelwidth}{\TPpagewidth}%     Width.
\newcommand{\toppanelheight}{\TPpageheight/5}% Height.
\newcommand{\toppanelshift}{0pt}%              Space between left screen edge and left edge of top panel.

% Dimensions of bottom panel.
\newcommand{\bottompanelwidth}{\TPpagewidth}%     Width.
\newcommand{\bottompanelheight}{\TPpageheight/5}% Height.
\newcommand{\bottompanelshift}{0pt}%              Space between left screen edge and left edge of bottom panel.

% Dimensions of left panel.
\newcommand{\leftpanelwidth}{\TPpagewidth/5}% Width.
\newcommand{\leftpanelheight}{\TPpageheight}% Height.
\newcommand{\leftpanelraise}{0pt}%            Space between bottom screen edge and bottom edge of left panel.

% Dimensions of right panel.
\newcommand{\rightpanelwidth}{\TPpagewidth/5}% Width.
\newcommand{\rightpanelheight}{\TPpageheight}% Height.
\newcommand{\rightpanelraise}{0pt}%            Space between bottom screen edge and bottom edge of left panel.


%-----------------------------------------------------------------------------------------------------------------------
% Some internal panel parameters.

% Storage for panel contents.
\newcommand*{\toppanelcontents@TP}{}
\newcommand*{\bottompanelcontents@TP}{}
\newcommand*{\leftpanelcontents@TP}{}
\newcommand*{\rightpanelcontents@TP}{}


%-----------------------------------------------------------------------------------------------------------------------
% Panel-specific user level commands.

% \DeclarePanel[<name>]{<pos>}{<contents>} declares the contents <contents> of the panel at position <pos>.
% Afterwards, on every page the panel contents are set in a parbox of dimensions and position specified by
% <pos>panelwidth, <pos>panelheight, \panelmargin and <pos>panelshift for top and bottom panels and <pos>panelraise for
% left and right panels. The parbox is constructed anew on every page, so all changes influencing panel contents or
% parameters (like a \thepage in the panel contents) are respected.
% 
% The panel contents are set in color <pos>paneltextcolor. There is another standard color <pos>panelcolor, which is
% however not activated by \DeclarePanel but by selecting an appropriate background style.
% Note that pages are constructed as follows: first the page background, then the panels, and then the page
% contents. Hence, panels overwrite the background and the page contents overwrite the panels. The user is supposed to
% make sure themselves that there is enough space left on the page for the panels (document class specific settings).
% The panel declaration is global. A panel can be `undeclared' by using \DeclarePanel{<pos>}{}.
%
% There is a starred version which will (try to) automatically calculate the `flexible' dimension of each panel. For top
% and bottom panels this is the height, for left and right panels this is the width. Make sure the panel contents are
% `valid' at the time \DeclarePanel* is called so the calculation can be carried out in a meaningful way.
% While the automatic calculation of the height of top and bottom panels is trivial (using \settoheight), there is a
% sophisticated procedure for calculating a `good' width for the parbox containing the panel. Owing to limitations set
% by TeX, there are certain limits to the sophistication of the procedure. For instance, any `whatsits' (specials (like
% color changes), file accesses (like \label), or hyper anchors) or rules which are inserted directly in the vertical
% list of the parbox `block' the analysis, so the procedure can't `see' past them (starting at the bottom of the box)
% when analysing the contents of the parbox. The user should make sure such items are set in horizontal mode (by using
% \leavevmode or enclosing stuff in boxes). Furthermore, only overfull and underfull hboxes which occur while setting
% the parbox are considered when judging which width is `best'. This will reliably make the width large enough to
% contain `wide' objects like tabulars, logos and buttons, but might not give optimal results for justified text.
% vboxes occurring directly in the vbox are ignored.
% Note further that hboxes with fixed width (made by \hbox to...) which occur directly in the vbox may disturb the
% procedure, because the fixed width cannot be recovered. These hboxes will be reformatted with the width of the vbox,
% generating an extremely large badness, unsettling the calculation of maximum badness. To avoid this such hboxes should
% be either contained in a vbox or set in horizontal mode with appropriate glue at the end.
%
% If the optional argument <name> is given, the panel contents and (calculated) size will also be stored under the given
% name, to be restored later with \restorepanels. This is nice for switching between different sets of panels.
\newcommand{\DeclarePanel}{\@ifstar\auto@declarepanel@TP\declarepanel@TP}

\newcommand{\declarepanel@TP}[3][]%                          Non-starred version of \DeclarePanel.
{%
  \expandafter\gdef\csname #2panelcontents@TP\endcsname{#3}% Just store panel contents.
  \ifthenelse{\equal{#1}{}}{}{\csname store#2panel@TP\endcsname{#1}}% If <name> was given, store panel parameters away.
  }%

% Store away top panel parameters.
\newcommand{\storetoppanel@TP}[1]
{%
  \expandafter\global\expandafter\let\csname toppanelcontents@TP@#1\endcsname\toppanelcontents@TP% Contents.
  \expandafter\global\expandafter\let\csname toppanelwidth@TP@#1\endcsname\toppanelwidth@TP%       Width.
  \expandafter\global\expandafter\let\csname toppanelheight@TP@#1\endcsname\toppanelheight@TP%     Height.
  \expandafter\global\expandafter\let\csname toppanelshift@TP@#1\endcsname\toppanelshift@TP%       Raise.
}

% Store away bottom panel parameters.
\newcommand{\storebottompanel@TP}[1]
{%
  \expandafter\global\expandafter\let\csname bottompanelcontents@TP@#1\endcsname\bottompanelcontents@TP%
  \expandafter\global\expandafter\let\csname bottompanelwidth@TP@#1\endcsname\bottompanelwidth@TP%
  \expandafter\global\expandafter\let\csname bottompanelheight@TP@#1\endcsname\bottompanelheight@TP%
  \expandafter\global\expandafter\let\csname bottompanelshift@TP@#1\endcsname\bottompanelshift@TP%
}

% Store away left panel parameters.
\newcommand{\storeleftpanel@TP}[1]
{%
  \expandafter\global\expandafter\let\csname leftpanelcontents@TP@#1\endcsname\leftpanelcontents@TP%
  \expandafter\global\expandafter\let\csname leftpanelwidth@TP@#1\endcsname\leftpanelwidth@TP%
  \expandafter\global\expandafter\let\csname leftpanelheight@TP@#1\endcsname\leftpanelheight@TP%
  \expandafter\global\expandafter\let\csname leftpanelraise@TP@#1\endcsname\leftpanelraise@TP%
}

% Store away right panel parameters.
\newcommand{\storerightpanel@TP}[1]
{%
  \expandafter\global\expandafter\let\csname rightpanelcontents@TP@#1\endcsname\rightpanelcontents@TP%
  \expandafter\global\expandafter\let\csname rightpanelwidth@TP@#1\endcsname\rightpanelwidth@TP%
  \expandafter\global\expandafter\let\csname rightpanelheight@TP@#1\endcsname\rightpanelheight@TP%
  \expandafter\global\expandafter\let\csname rightpanelraise@TP@#1\endcsname\rightpanelraise@TP%
}


\newcommand{\auto@declarepanel@TP}[2]%                           Starred version of \DeclarePanel.
{\csname calc#1dimen@TP\endcsname{#2}\declarepanel@TP{#1}{#2}} % Calculate `optimal' dimension and store contents.

% Restore panel parameters stored away under a given name.
\newcommand{\restorepanels}[1]
{%
  \@ifundefined{toppanelcontents@TP@#1}{\global\let\toppanelcontents@TP\empty}
  {%
    \expandafter\global\expandafter\let\expandafter\toppanelcontents@TP\csname toppanelcontents@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\toppanelwidth@TP\csname toppanelwidth@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\toppanelheight@TP\csname toppanelheight@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\toppanelshift@TP\csname toppanelshift@TP@#1\endcsname
    }%
  \@ifundefined{bottompanelcontents@TP@#1}{\global\let\bottompanelcontents@TP\empty}
  {%
    \expandafter\global\expandafter\let\expandafter\bottompanelcontents@TP\csname bottompanelcontents@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\bottompanelwidth@TP\csname bottompanelwidth@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\bottompanelheight@TP\csname bottompanelheight@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\bottompanelshift@TP\csname bottompanelshift@TP@#1\endcsname
    }%
  \@ifundefined{leftpanelcontents@TP@#1}{\global\let\leftpanelcontents@TP\empty}
  {%
    \expandafter\global\expandafter\let\expandafter\leftpanelcontents@TP\csname leftpanelcontents@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\leftpanelwidth@TP\csname leftpanelwidth@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\leftpanelheight@TP\csname leftpanelheight@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\leftpanelraise@TP\csname leftpanelraise@TP@#1\endcsname
    }%
  \@ifundefined{rightpanelcontents@TP@#1}{\global\let\rightpanelcontents@TP\empty}
  {%
    \expandafter\global\expandafter\let\expandafter\rightpanelcontents@TP\csname rightpanelcontents@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\rightpanelwidth@TP\csname rightpanelwidth@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\rightpanelheight@TP\csname rightpanelheight@TP@#1\endcsname
    \expandafter\global\expandafter\let\expandafter\rightpanelraise@TP\csname rightpanelraise@TP@#1\endcsname
    }%
}

%-----------------------------------------------------------------------------------------------------------------------
% Implementation of automatic dimension calculation.

% Interface to the horizontal and vertical calculation procedures. The first argument is being recalculated, the second
% and third ones are parameters.
\newcommand{\calctopdimen@TP}[1]{\calcvdimen@TP{\toppanelheight}{\toppanelwidth}{#1}}
\newcommand{\calcbottomdimen@TP}[1]{\calcvdimen@TP{\bottompanelheight}{\bottompanelwidth}{#1}}
\newcommand{\calcleftdimen@TP}[1]{\calchdimen@TP{\leftpanelwidth}{\leftpanelheight}{#1}}%
\newcommand{\calcrightdimen@TP}[1]{\calchdimen@TP{\rightpanelwidth}{\rightpanelheight}{#1}}%

% Remove any contents which could mess up the box analysis.
\newcommand{\panel@sanitize@TP}
{%
  \let\hyperlink=\@secondoftwo
  \let\Acrobatmenu=\@secondoftwo
}

% Calculate height of `horizontal' panel.
\newcommand{\calcvdimen@TP}[3]
{%
  \setbox\tempbox@TP=\hbox{\panel@sanitize@TP\@@mk@panel@TP{#2}{}{toppaneltextcolor}{#3}}% Set panel into a dummy box.
  \mklength@TP{#1}{\ht\tempbox@TP+\dp\tempbox@TP}%                                       % Measure total height.
}

% Calculate `optimal' width of `vertical panel.
\newcommand{\calchdimen@TP}[3]
{%
  \optwidth@TP{#1}{#2-\panelmargin*2}%              Calculate `optimal' width of a parbox. Panel margins are respected.
  {.5\textwidth-\panelmargin*2}{\panelalignment#3}% .5\textwidth is the hardcoded absolute maximum width.
  \mklength@TP{#1}{#1+\panelmargin*2}%
  }

% User-configurable: Which `resolution' should be used when searching for `best' width?
\newcommand{\optwidthsteps}{100}

% User-configurable: Which badness should be tolerated as `perfect' (stopping the search for a better one).
\newcommand{\optwidthlinetolerance}{200}

% Internal parameter: Badness of the parbox currently under consideration.
\let\maxbadness@TP=\@tempcnta

% A hook to disable some commands which would be in the way while measuring things.

\def\optwidthdisablecommands@TP
{%
  \let\Hy@colorlink\@firstofone
  \let\Hy@endcolorlink\relax
  }

% Calculate `best' width of a parbox. The current algorithm will set the textual contents into parboxes of increasing
% width, starting from 0pt and ending with the maximum width given, in \optwidthsteps steps. The `badness' of every
% parbox is measured. If it is below the threshold defined by \optwidthlinetolerance, the process is stopped and the
% found width accepted. If this doesn't happen, the width of the parbox with the least badness is returned.
\newcommand{\optwidth@TP}[4]
{%
  \setcounter{tmpcnta@TP}{0}%                                  Initialize `probe counter' for box width.
  \let\best@cnt@TP=\empty%                                     Initialize number of best `probe' so far.
  \def\bestbadness@TP{1000000}%                                Initialize badness of best `probe'.
  \setboolean{carryon@TP}{true}%                               Flag for breaking out of loop.
  \setlength{\tempdimb@TP}{#2}%                                Store maximal box height.
  \whiledo
  {\value{tmpcnta@TP}<\optwidthsteps\and\boolean{carryon@TP}}% Probes done or break of loop?
  {%
    \stepcounter{tmpcnta@TP}%                                  Start next probe.
    \setbox\@tempboxa=\hbox%                                   The trick with vbox/lastbox is to get the vbox
    {%                                                         produced by \parbox `immediately' into a box register.
      \optwidthdisablecommands@TP%                             Turn off some nasties not needed when measuring.
      \parbox[b]{(#3)/\optwidthsteps*\value{tmpcnta@TP}}%      Make the next parbox.
      {\hfuzz\maxdimen\hbadness\@M\relax#4}%
      \global\setbox\tempbox@TP=\lastbox%                      ... and assign \tempbox@TP to it.
      }%
    \setlength{\tempdima@TP}{\ht\tempbox@TP+\dp\tempbox@TP}%   Measure total height.
    \ifthenelse{\lengthtest{\tempdima@TP>\tempdimb@TP}}%       If it exceeds the maximum height given, the box isn't 
    {}%                                                        acceptable anyway.
    {%
      \calcmaxbadness@TP{\maxbadness@TP}{\tempbox@TP}%         Calculate `worst badness' of any hbox appearing in parbox.
      \ifthenelse{\not\maxbadness@TP>\optwidthlinetolerance}%  Below Threshold?
      {% Yes. Accept this width.
        \edef\best@cnt@TP{\thetmpcnta@TP}%                     Store this probe number.
        \setboolean{carryon@TP}{false}%                        Break loop.
        }
      {% No. Carry on.
        \ifthenelse{\maxbadness@TP<\bestbadness@TP}%           Below lowest badness found so far?
        {% Yes. Store probe number.
          \edef\bestbadness@TP{\number\maxbadness@TP}%         Store badness value.
          \edef\best@cnt@TP{\thetmpcnta@TP}%                   Store probe number.
          }
        {}% No. Try next probe.
        }% matches second argument of \ifthenelse{\not\maxbadness@TP>\optwidthlinetolerance}%
      }% matches second argument of \ifthenelse{\lengthtest{\tempdima@TP>\tempdimb@TP}}%
    }% matches \whiledo{\value{tmpcnta@TP}<\optwidthsteps\and\boolean{carryon@TP}}{%
  \ifx\best@cnt@TP\empty%                                      Was _any_ badness below the initialization value found?
    \mklength@TP{#1}{#3}% No; return max width.                                   
   \else
    \mklength@TP{#1}{(#3)/\optwidthsteps*\best@cnt@TP}% Yes; return width of best probe.
  \fi
  }% matches \newcommand{\optwidth@TP}[4]{%

% Calculate maximal badness of any hbox occurring in a vbox.
\newcommand{\calcmaxbadness@TP}[2]
{%
  \let\@resultcnt@TP=#1%           Here we store the result.
  \global\@resultcnt@TP=\z@\relax% Just in case no hbox occurs...
  \setlength{\@tempdima}{\wd#2}%   This is the width to which every hbox is stretched for finding its badness.
  \setbox\@tempboxa=\vbox%         A dummy vbox for recursively analysing the vbox contents using \lastbox
  {%
    \hfuzz\maxdimen\hbadness\@M
    \unvbox#2%                     `free' the contents of the vbox.
    \measureboxes@TP%              Analyse `tail to head' using \lastbox.
    }%
  }


% Recursively analyse vertical list using \lastbox, to find maximum badness of any contained hbox.
\newcommand{\measureboxes@TP}%
{%
  \unskip\unpenalty\unkern%    This is a kluge for TeX, because there is no certain way of finding out whether there's a 
  \unskip\unpenalty\unkern%    penalty, glue or kern on the vertical list. \lastpenalty will give its value, but a 
  \unskip\unpenalty\unkern%    value of 0 might mean there was none or there was one of value 0.
  \unskip\unpenalty\unkern%    This is different in eTeX. I might make a switch to a smarter solution.
  \unskip\unpenalty\unkern
  \unskip\unpenalty\unkern
  \unskip\unpenalty\unkern
  \unskip\unpenalty\unkern
  \unskip\unpenalty\unkern
  \unskip\unpenalty\unkern
  \setbox\@tempboxa=\lastbox% Grab last box.
  \ifhbox\@tempboxa%          Was this an hbox?
    \setbox0=\hb@xt@\@tempdima{\unhbox\@tempboxa}% Yes. Reformat with given width.
    \ifnum\badness>\@resultcnt@TP%                 Badness larger than largest recorded badness?
      \global\@resultcnt@TP=\badness%              Yes. Memorize.
    \fi
    \expandafter\measureboxes@TP%                  Recursive call.
   \else
    \ifvbox\@tempboxa%                                      Was this a vbox?
      \expandafter\expandafter\expandafter\measureboxes@TP% Ignore, but execute recursive call.
    \fi
  \fi
  }


%-----------------------------------------------------------------------------------------------------------------------
% Actually typeset panels.        

\newcommand{\mk@toppanel@TP}% top panel
{%
  \ifx\toppanelcontents@TP\empty%           top panel specified?
   \else%                                   Yes; create box with appropriate dimensions, background color and contents.
    \@mk@panel@TP{\toppanelwidth}{\toppanelheight}{toppaneltextcolor}{\toppanelcontents@TP}%
  \fi
  }

\newcommand{\mk@bottompanel@TP}% bottom panel
{%
  \ifx\bottompanelcontents@TP\empty%        bottom panel specified?
   \else%                                   Yes; create box with appropriate dimensions, background color and contents.
    \@mk@panel@TP{\bottompanelwidth}{\bottompanelheight}{bottompaneltextcolor}{\bottompanelcontents@TP}%
  \fi
  }

\newcommand{\mk@leftpanel@TP}% left panel
{%
  \ifx\leftpanelcontents@TP\empty%          left panel specified?
   \else%                                   Yes; create box with appropriate dimensions, background color and contents.
    \@mk@panel@TP{\leftpanelwidth}{\leftpanelheight}{leftpaneltextcolor}{\leftpanelcontents@TP}%
  \fi
  }

\newcommand{\mk@rightpanel@TP}% right panel
{%
  \ifx\rightpanelcontents@TP\empty%         right panel specified?
   \else%                                   Yes; create box with appropriate dimensions, text color and contents.
    \@mk@panel@TP{\rightpanelwidth}{\rightpanelheight}{rightpaneltextcolor}{\rightpanelcontents@TP}%
  \fi
  }


\newcommand{\@mk@panel@TP}[2]% Generate `standard' parbox parameters for panels.
{%
  \@@mk@panel@TP{#1}{[#2-\panelmargin*2][s]}%
  }
    

\@ifclassloaded{powersem}
{%
  \newcommand{\panelalignment}{\sem@ptsize{\slide@ptsize}\large\normalsize}%
}
{%
  \newcommand{\panelalignment}%            Justification for panels. This setting allows a certain amount of 
  {\setlength{\rightskip}{0pt plus 20pt}}% `right-raggedness'. Leave empty for standard parbox formatting.
}

% Make a panel box.
\newcommand{\@@mk@panel@TP}[4]
{%
  \vbox
  {%
    \offinterlineskip    
    \kern\panelmargin%  Top margin.
    \hbox
    {{%
        \ifthenelse{\boolean{instepwise@TP}}%  Inside \stepwise, colors mat have been dimmed, leaking out to panels.
        {\usecolorset{stwcolors}}{}%           Restore them, just in case.
        \color{#3}%                            Set panel text color.
        \kern\panelmargin%                     Left margin.
        \parbox[b]#2{#1-\panelmargin*2}%       The parbox with the main panel contents.
        {%
          \normalfont
          \panelalignment#4%
          \hrule\@height\z@%            The hrule makes sure the total height of this box can be measured appropriately.
          }% 
        \kern\panelmargin%              Right margin.
        }}%
    \kern\panelmargin%                  Bottom margin.
    }%
  }
    

%=======================================================================================================================
% Navigation helpers.
%
% The following code is rather preliminary and provides only the very basics for making navigation buttons and such. If
% you're using a package which allows to do this, don't even consider using the following. 

%-----------------------------------------------------------------------------------------------------------------------
% Some configurable button parameters.

% Space between button label and border.
\newcommand{\buttonsep}{\fboxsep}            

% Width of button frame.
\newcommand{\buttonrule}{0pt}

% Horizontal displacement of button shadow.
\newcommand{\buttonshadowhshift}{.3\fboxsep}

% Vertical displacement of button shadow.
\newcommand{\buttonshadowvshift}{-.3\fboxsep}


%-----------------------------------------------------------------------------------------------------------------------
% Button-specific user level commands.

% \button[<width>][<height>][<depth>][<alignment>]{<navcommand>}{<text>} creates a button labelled <text> which executes
% <navcommand> when pressed.
% <navcommand> can be for instance \Acrobatmenu{<command>} or \hyperlink{<target>} (note that <navcommand> should take
% one (more) argument specifying the sensitive area which is provided by \button). 
% If given, the optional parameters <width>, <height>, and <depth> give the width, height and depth, respectively, of
% the framed area comprising the button (excluding the shadow, but including the frame). Default are the `real' width,
% height and depth, respectively, of <text>, plus allowance for the frame.
% If given, the optional parameter <alignment> (one of l,c,r) gives the alignment of <text> inside the button box (makes
% sense only if <width> is given).
\newcommand{\button}[1][0pt]%      Collect first optional parameter.
{%
  \mklength@TP\bt@width@TP{#1}%    Store optional argument.
  \button@TP
}

\newcommand{\button@TP}[1][0pt]%   Collect second optional parameter.
{%
  \mklength@TP\bt@height@TP{#1}%   Store optional argument.
  \@button@TP
}

\newcommand{\@button@TP}[1][0pt]%  Collect third optional parameter.
{%
  \mklength@TP\bt@depth@TP{#1}%    Store optional argument.
  \@@button@TP
}

\newcommand{\@@button@TP}[3][c]%   Collect fourth optional and two mandatory parameters and proceed.
{%
  \ifthenelse{\lengthtest{\bt@width@TP=0pt}}%       <width> given?
  {\mklength@TP{\bt@width@TP}{\widthof{#3}}}%       No. Calculate width of <text>.
  {\mklength@TP{\bt@width@TP}{\bt@width@TP-\buttonsep*2-\buttonrule*2}}% Yes. Calculate area left for <text>.
  \ifthenelse{\lengthtest{\bt@height@TP=0pt}}%      <height> given?
  {\mklength@TP{\bt@height@TP}{\heightof{#3}}}%     No. Calculate height of <text>.
  {\mklength@TP{\bt@height@TP}{\bt@height@TP-\buttonsep-\buttonrule}}% Yes. Calculate area left for <text>.
  \ifthenelse{\lengthtest{\bt@depth@TP=0pt}}%       <depth> given?
  {\mklength@TP{\bt@depth@TP}{\depthof{#3}}}%       No. Calculate depth of <text>.
  {\mklength@TP{\bt@depth@TP}{\bt@depth@TP-\buttonsep-\buttonrule}}% Yes. Calculate area left for <text>.
  \leavevmode% \rlap creates a `raw' hbox. So we get into horizontal mode.
  \rlap%       Make shadow.
  {%
    \hspace*{\buttonshadowhshift}%  Horizontal displacement.
    \raisebox{\buttonshadowvshift}% Vertical displacement.
    {%
      {% Inner group for correct color handling.
        \setcolor@TP{buttonshadowcolor}% Button shadow color.
        \rule%                           Create colored rectangular patch of appropriate dimensions.
        [-\bt@depth@TP-\buttonsep-\buttonrule]
        {\bt@width@TP+\buttonsep*2+\buttonrule*2}
        {\bt@height@TP+\bt@depth@TP+\buttonsep*2+\buttonrule*2}%
        }% matches inner group
      }% matches \raisebox{\buttonshadowvshift}{%
    }% matches \rlap{%
  \edef\o@fboxrule@TP{\the\fboxrule}%    Preserve original definitions of \fbox parameters.
  \edef\o@fboxsep@TP{\the\fboxsep}%
  #2%                                    Execute <navcommand>.
  {%
    \setlength{\fboxrule}{\buttonrule}%        Set \fbox parameters for button frame.
    \setlength{\fboxsep}{\buttonsep}%
    \fcolorbox{buttonframecolor}{buttoncolor}% Create button frame with the right colors.
    {%
      \makebox[\bt@width@TP][#1]%              Create box of correct width to contain <text>.
      {%
        \raisebox{0pt}[\bt@height@TP][\bt@depth@TP]% Create box of correct height and depth.
        {%
          \setlength{\fboxrule}{\o@fboxrule@TP}\setlength{\fboxsep}{\o@fboxsep@TP}% Restore fbox parameters.
          \setcolor@TP{buttontextcolor}#3%           Produce <text>. 
          }% matches \raisebox{0pt}[\bt@height@TP][\bt@depth@TP]{%
        }% matches \makebox[\bt@width@TP][#1]{%
      }% matches \fcolorbox{buttonframecolor}{buttoncolor}{%
    }% matches argument of <navcommand>.
  }% matches \newcommand{\@@button@TP}[3][c]{%


% Some predefined buttons.

% Size of predefined button symbols.
\newcommand{\buttonsymbolsize}{\footnotesize}

% Define predefined button symbols.
\@ifpackageloaded{amssymb}%     AMS symbols available?
{% Yes. Use `black' symbols.
  \newcommand{\buttonleftarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\blacktriangleleft}}}%   `left' arrow.
  \newcommand{\buttonrightarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\blacktriangleright}}}% `right' arrow.
  \newcommand{\buttonbackarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\vartriangleleft}}}%     `back' arrow.
}
{% No. Use replacements from standard set.
  \newcommand{\buttonleftarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\lhd}}}%       `left' arrow.
  \newcommand{\buttonrightarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\rhd}}}%      `right' arrow.
  \newcommand{\buttonbackarrowsymbol}{{\buttonsymbolsize\boldmath\origmath{\leftarrow}}}% `back' arrow.
}

% Width of predefined buttons.
\newcommand{\stdbuttonwidth}{\widthof{\buttonrightarrowsymbol\buttonrightarrowsymbol\buttonrightarrowsymbol}+4pt}

% Customizeable default: How to find the number of the current page?
\newcommand{\currentpagevalue}{\value{page}}


% Predefined button: last subpage of previous page.
\newcommand{\backpagebutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\setcounter{tmpcnta@TP}{\currentpagevalue-1}\hyperlink{page.\thetmpcnta@TP}}
  {\buttonleftarrowsymbol\buttonleftarrowsymbol}%
  }

% Predefined button: previous step.
\newcommand{\backstepbutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\Acrobatmenu{PrevPage}}
  {\buttonleftarrowsymbol}%
  }

% Predefined button: `undo action' (go back to whatever was before last action).
\newcommand{\gobackbutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\Acrobatmenu{GoBack}}
  {\buttonbackarrowsymbol}%
  }

% Predefined button: next step.
\newcommand{\nextstepbutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\Acrobatmenu{NextPage}}
  {\buttonrightarrowsymbol}%
  }

% Predefined button: first subpage of next page.
\newcommand{\nextpagebutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\setcounter{tmpcnta@TP}{\currentpagevalue+1}\hyperlink{firstpage.\thetmpcnta@TP}}
  {\buttonrightarrowsymbol\buttonrightarrowsymbol}%
  }

% Predefined button: last subpage of next page.
\newcommand{\nextfullpagebutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\setcounter{tmpcnta@TP}{\currentpagevalue+1}\hyperlink{page.\thetmpcnta@TP}}
  {\buttonrightarrowsymbol\buttonrightarrowsymbol\buttonrightarrowsymbol}%
  }

% Predefined button: toggle fullscreen mode.
\newcommand{\fullscreenbutton}[1][\stdbuttonwidth]
{%
  \button[#1]{\Acrobatmenu{FullScreen}}
  {\buttonrightarrowsymbol\buttonleftarrowsymbol}%
  }

%=======================================================================================================================
% Set acrobat reader's page transition mode.
%
% Most of the following is snarfed from an email message of Marc van Dongen to the ppower4 mailing list on Thu, 7 Oct
% 1999. 
% Thanks to Marc for his permission to include his code into this package.

% \pagetransition{<setting>} is a generic command for setting the page transition with hyperref's \hypersetup. The
% command is defined to a noop in case hyperref is not loaded.
\ifthenelse{\boolean{display}}%            Are dynamic features enabled?
{% Yes.
  \newcommand{\pagetransition}[1]%         Definition for preamble.
  {%
    \@ifpackageloaded{hyperref}%           Can we use \hypersetup?
    {% Yes.
      \hypersetup{pdfpagetransition={#1}}% Set page transition with \hypersetup.
      }
    {% No. In this case, we can't set the page transition.
      \PackageWarning{texpower}
      {Package hyperref not loaded.\MessageBreak Page transition not set}%
      }%
    }% matches \newcommand{\pagetransition}[1]{%
  \AtBeginDocument%                      Definition for document body.
  {%
    \@ifpackageloaded{hyperref}%         Can we use \hypersetup?
    {% Yes.
      \hypersetup{pdfpagetransition={}}% Make pagetransition setting (consistently) local to groups.
      \renewcommand{\pagetransition}[1]{\hypersetup{pdfpagetransition={#1}}}%
      }
    {% No. Disable page transitions.
      \PackageWarning{texpower}
      {Package hyperref not loaded.\MessageBreak Page transitions disabled}%
      \let\pagetransition=\@gobble
      }% 
    }% matches \AtBeginDocument{%
  }% matches \ifthenelse{\boolean{display}}{%
{\let\pagetransition=\@gobble}% No. Disable page transitions.


\newcommand{\pageTransitionSplitHO}{\pagetransition{Split /Dm /H /M /O}}% Split Horizontally to the outside.

\newcommand{\pageTransitionSplitHI}{\pagetransition{Split /Dm /H /M /I}}% Split Horizontally to the inside.

\newcommand{\pageTransitionSplitVO}{\pagetransition{Split /Dm /V /M /O}}% Split Vertically to the outside.

\newcommand{\pageTransitionSplitVI}{\pagetransition{Split /Dm /V /M /I}}% Split Vertically to the inside.

\newcommand{\pageTransitionBlindsH}{\pagetransition{Blinds /Dm /H}}% Horizontal Blinds.

\newcommand{\pageTransitionBlindsV}{\pagetransition{Blinds /Dm /V}}% Vertical Blinds.

\newcommand{\pageTransitionBoxO}{\pagetransition{Box /M /O}}% Growing Box.

\newcommand{\pageTransitionBoxI}{\pagetransition{Box /M /I}}% Shrinking Box.

% argument must be number fom 0 to 360
\newcommand{\pageTransitionWipe}[1]{\pagetransition{Wipe /Di #1}}% Wipe from one edge of the page to the facing edge.

\newcommand{\pageTransitionDissolve}{\pagetransition{Dissolve}}% Dissolve.
 
% argument must be number fom 0 to 360
\newcommand{\pageTransitionGlitter}[1]{\pagetransition{Glitter /Di #1}}% Glitter from one edge to the facing edge.

\newcommand{\pageTransitionReplace}{\pagetransition{Replace}}% Simple Replace (the default). 



%=======================================================================================================================
% Set acrobat reader's automatic page advancing feature.
%
% \pageDuration{<d>} will force pages to be advanced automatically after <d> seconds when in full screen mode. The
% effect starts on the current page and is undone by a group end or the command \stopAdvancing. <d> should be a
% (fixed-point) number. 
%
% Note a very strange behaviour of acrobat and acroread v4.05 and onwards: Automatic advancing is disabled unless
% explicitly enabled by the ``advance every _<n>_ seconds'' setting in the full screen dialogue. But in this case, all
% pages not having any page duration setting will be advanced after <n> seconds. As another trap, at least in some
% versions of acroread and acrobat, the maximum for <n> when set in the dialogue is 60 seconds. To make matters even
% worse, there seems to be a (quite arbitrary) even for duration setting of pages: 546 seconds (about nine minutes).
% This leaves you with the following options if you want to use automated advancing in your presentations (for animation
% effects, say):
% 
% a) You're using a version of acrobat or acroread predating 4.05 (or any other version where this misbehaviour
% miraculously isn't present): All is well, nothing to do.
%
% b) You're using a `buggy' version where more than 60 seconds can be set as a value for <n> in the full screen dialogue
% (I'm not sure whether such a beast exists; maybe both `features' coincide): Just activate automatic advancing in the
% full screen dialogue and set an `infinite' number of seconds (3600, say). This value is masked by an explicit setting
% using \pageDuration, so animations will still work.
%
% c) You're using a `buggy' version with a maximum dialogue setting of 60, but you're comfortable with your presentation
% always advancing automatically at least every 60 seconds: Set <n> to 60 and proceed as above.
%
% d) You're using a `buggy' version with a maximum dialogue setting of 60 and you're comfortable with your presentation
% always advancing automatically at least every 546 seconds (9.1 minutes): Give the package option ``nineminutes'' to
% texpower. This will put an explicit duration setting of 546 seconds on every page (overridden by explicit settings
% using \pageDuration). Set the advancing time in the full screen dialogue to anything; it will be ignored because every
% page has an explicit setting.
%
% e) You're using a `buggy' version with a maximum dialogue setting of 60, you'd like your presentation to advance more
% slowly than every 546 seconds and your version of acroread or acrobat miraculously doesn't have the upper bound of 546
% seconds (which I've empirically discovered with acrobat 5.0 on Win NT): Put \renewcommand{\infinitepageduration}{3600}
% in your preamble and see what happens. If the value is too high, acroread will go into fast forward mode or do other
% strange things. Otherwise: Lucky you.
%
% f) You're using a `buggy' version with a maximum dialogue setting of 60, you'd like your presentation to advance more
% slowly than every 546 seconds and your version of acroread or acrobat also has the upper bound of 546 seconds: In this
% case you're out of luck. Of course you can try to get the guys at adobe to clean up this whole mess. Good luck with
% that! 

% If \infinitepageduration is set to empty, then a page duration setting will appear only where \pageDuration was
% used. Otherwise, every page without explicit setting gets a page duration of \infinitepageduration.

\newcommand{\infinitepageduration}{}%          Default: No page duration setting on every page.

\ifthenelse{\boolean{nineminutes@TP}}%         If the option nineminutes is given, every page without explicit setting
{\renewcommand{\infinitepageduration}{546}}{}% gets a setting of 546 seconds (9.1 minutes).

% Implementation of \pageDuration.
\ifthenelse{\boolean{display}}%            Are dynamic features enabled?
{% Yes.
  \newcommand{\pageDuration}[1]%           Definition for preamble.
  {%
    \@ifpackageloaded{hyperref}%           Can we use \hypersetup?
    {% Yes.
      \hypersetup{pdfpageduration={#1}}%   Set page duration with \hypersetup.
      }%
    {% No. In this case, we can't set the page duration.
      \PackageWarning{texpower}
      {Package hyperref not loaded.\MessageBreak Page duration not set}%
      }%
    }% matches \newcommand{\pageDuration}[1]{% 
  \AtBeginDocument%                        Make sure this also works if texpower is loaded before hyperref.
  {%
    \@ifpackageloaded{hyperref}%                    Can we use \hypersetup?
    {% Yes.
      \edef\next{\noexpand\hypersetup{pdfpageduration={\infinitepageduration}}}%
      \next%                                        Set default page duration.
      \renewcommand{\pageDuration}[1]{\hypersetup{pdfpageduration={#1}}}% Set page duration with \hypersetup.
      }%
    {% No. In this case, we can't set the page duration.
      \PackageWarning{texpower}
      {Package hyperref not loaded.\MessageBreak Page duration disabled}%
      \let\pageDuration=\@gobble
      }%
    }% matches \AtBeginDocument{% 
  }% matches \ifthenelse{\boolean{display}}{%
{\let\pageDuration=\@gobble}% No. Disable page duration.

% \stopAdvancing undoes any setting effected by \pageDuration.
\newcommand{\stopAdvancing}
{\edef\next{\noexpand\pageDuration{\infinitepageduration}}\next}% Reset to default page duration.


%=======================================================================================================================
% TeXPower kernel.
%
% This area contains the `low level' implementation of TeXPowers central functions. Mainly, (La)TeX's \shipout and
% \output routines are overloaded, adding some necessary functionality (duplication of page contents for incremental
% page building; display of backgrounds and panels).
% Also, the user command \pause is implemented here, using the kernel functions for saving and restoring page contents.
% 
% The code for overloading the output routine is derived from Klaus Guntermanns texpause package which can be obtained
% from the PPower4 Web site 
%
% http://www-sp.iti.informatik.tu-darmstadt.de/software/ppower4/
%
% Thanks to Heiko Oberdiek for his suggestion how \leaders can be used to disable processing of whatsits in the
% duplicated text.
%
% The code for overloading \shipout is derived from everyshi.sty with permission by Martin Schroeder.

%-----------------------------------------------------------------------------------------------------------------------
% Overload \shipout.

% Overloading is done at the beginning of the document just in case some other package messes with \shipout.
\AtBeginDocument{\shipoutinit@TP}%  

% Replace \shipout by own definition.
\newcommand*{\shipoutinit@TP}
{%
  \let\o@shipout@TP=\shipout% Memorize previous definition.
  \let\shipout\shipout@TP%    Replace by own one.
  }%

% Our own version of \shipout takes the offered box and passes it to another routine for further inspection.
\newcommand{\shipout@TP}
{%
  \afterassignment\shipout@test@TP
  \global\setbox\@cclv= %
  }%

% If \shipout is called with an argument of the form \box<n>, then the box will have indeed been assigned to \@cclv at
% the time \shipout@test@TP is called. In this case, \shipout@output@TP is called immediately. If \shipout is called
% with an argument of the form \vbox{...}, then \shipout@test@TP is called at the beginning of the box definition,
% _before_ the box is assigned (this is a feature of \afterassignment). In this case, the call of \shipout@output@TP is
% moved _after_ the box definition using \afetrgroup, so that \@cclv is correctly defined at the time \shipout@output@TP
% is executed.
\newcommand{\shipout@test@TP}
{%
  \ifvoid\@cclv\relax%               Is the box assigned yet?
    \aftergroup\shipout@output@TP%   No; defer execution of \shipout@output@TP.
   \else
    \shipout@output@TP%              Yes; execute \shipout@output@TP immediately.
  \fi%
  }%

% The main part of our redefinition of \shipout.
\newcommand{\shipout@output@TP}
{%
  \shipout@hook@TP%          Here, our own stuff is executed, manipulating \@cclv.
  \o@shipout@TP\box\@cclv%   Execute original shipout routine.
  }%


%-----------------------------------------------------------------------------------------------------------------------
% The kernel functions to be executed at \shipout.

% \AtShipout{<code>} will save <code> in a special place where it is executed at the time of the next \shipout (and then
% deleted). Needless to say it should not produce any output. This is mainly for placing anchors in a controlled way
% even inside incremental builds. 
\newcommand{\AtShipout}[1]
{\expandafter\gdef\expandafter\at@shipout@once@TP\expandafter{\at@shipout@once@TP#1}}% Add argument to container.

% The container for <code> stored away by \AtShipout. This is placed on the page by the next \shipout and then deleted.
\newcommand{\at@shipout@once@TP}{}

% Save the original definition of \hyper@@anchor.
\AtBeginDocument{\global\let\o@hyper@@anchor\hyper@@anchor}

% The following makes sure that a hyper target firstpage.<n> is placed on the _first_ subpage of every page. 
\@ifpackageloaded{hyperref}%                            Is hyperref loaded?
{% Yes. Prepare hook.
  \newcommand{\do@insert@firstanchor@TP}%               This is executed on the first subpage of every page.
  {\hypertarget{firstpage.\number\currentpagevalue}{}}% Create target.
  }
{\newcommand{\do@insert@firstanchor@TP}{}}% No. Leave hook empty.


\newcommand{\dont@insert@firstanchor@TP}{}% This is executed on every subpage which is _not_ the first one.

\newcommand{\insert@firstanchor@TP}{\do@insert@firstanchor@TP}% This is the hook itself which is executed on every page.


% The hook executed at every call of \shipout. It executes the following tasks:
% a) Filter out whatsits on duplicate pages.
% b) Put page background at the `lowest' layer.
% c) Put panels at the `second lowest' layer.
% d) Execute \AtShipout code and place hypertarget firstpage.<n>.
% e) Put \box\@cclv at `top' layer.
\newcommand{\shipout@hook@TP}
{%
  \filterpage@TP%                  Filter out whatsits on duplicate pages.
  \setbox\@cclv=%                  Create `real' page box (which is later shipped out).
  \hbox{%
    \set@typeset@protect
    \rlap%                         Place background box.
    {%
      \vtop to \TPpageheight
      {%      
        \offinterlineskip
        \hrule\@height\z@\relax
        \kern -1truein\relax
        \kern -\voffset\relax
        \moveleft 1truein\hbox{\kern-\hoffset\copy\bgndbox@TP}%
        \vss
        \kern 1truein\relax
        \kern\voffset\relax
        }%
      }%
    \rlap%                         Place `vertical' panels.
    {%
      \vtop to \TPpageheight
      {%      
        \offinterlineskip
        \hrule\@height\z@\relax
        \kern -1truein\relax
        \kern -\voffset\relax
        \moveleft 1truein\hb@xt@\TPpagewidth
        {%
          \kern-\hoffset\raise\leftpanelraise\hbox{\mk@leftpanel@TP}%
          \hfill
          \raise\rightpanelraise\hbox{\mk@rightpanel@TP}%
          \kern\hoffset
          }%
        \vss
        \kern 1truein\relax
        \kern\voffset\relax
        }%
      }%
    \rlap%                         Place `horizontal' panels.
    {%
      \vtop to \TPpageheight
      {%      
        \offinterlineskip
        \hrule\@height\z@\relax
        \kern -1truein\relax
        \kern -\voffset\relax
        \moveleft 1truein\hbox{\kern-\hoffset\kern\toppanelshift\mk@toppanel@TP}%
        \vfill
        \moveleft 1truein\hbox{\kern-\hoffset\kern\bottompanelshift\mk@bottompanel@TP}%
        \kern 1truein\relax
        \kern\voffset\relax
        }%
      }%
    \rlap
    {%
      \let\hyper@@anchor\o@hyper@@anchor%       Reactivate hyper anchors.
      \insert@firstanchor@TP%                   Execute hook for creating target firstpage.<n>
      \ifshippingduplicate%                     Will further subpages follow?
        \global\let\insert@firstanchor@TP=\dont@insert@firstanchor@TP% Deactivate hook for next page.
       \else
        \global\let\insert@firstanchor@TP=\do@insert@firstanchor@TP%   Reactivate hook for next page.
      \fi
      \at@shipout@once@TP%                      Execute code stored away by \AtShipout.
      }%
    \global\let\at@shipout@once@TP=\empty%      Clear \AtShipout container.
    \vtop%                                      Place `real' page contents.
    {%
      \offinterlineskip
      \hrule\@height\z@\relax
      \hbox{\box\@cclv}%
      }
    }%
  }


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of `fixcolorstack' option.

% The problem is this: dvips (and some other tools) maintains a color stack when converting dvi to ps. Its function is
% to always be able to correctly switch back to the previously used color even if there is a page break (and according
% typesetting of headers etc) inbetween switching to another color and switching back. 
% This has many advantages (pdftex, for instance, which doesn't maintain a color stack, always has problems to restore
% the correct text color afetr a page break).
% In connection with TeXPower, however, this leads o problems. For controlling the color stack, push and pop commands
% are inserted into the dvi using specials. At typesetting time, these specials are stored in the vertical list. When
% page contents are copied, it might be that the copy contains an unequal number of push and pop commands, which will
% make dvips's color stack go out of sync.
% To remedy this, texpower maintains a `counter stack' which should contain all color stack commands issued on the
% current page. Whenever a copied page is shipped out, appropriate color stack correction commands are issued to balance
% the stack.
% As this is necessary only for drivers implementing a color stack, the option is disabled for some drivers.

\def\colorcorrections@TP{\relax}%          The `counter stack' of color correction codes, reset at every \shipout.

\AtBeginDocument%                          Make sure to catch color.sty even if it's loaded after texpower.
{%
  \ifthenelse{\boolean{fixcolorstack@TP}}% Was the fixcolorstack option given?
  {%
    \@ifundefined{VTeXversion}%            Using vtex?
    {% No. Go on.
      \ifthenelse{\boolean{pdf}}%          Producing pdf with pdftex?
      {% Yes. Color stack fixing unnecessary.
        \PackageWarning{texpower}
        {pdftex doesn't need color stack correction.\MessageBreak Option fixcolorstack disabled.}%
        }
      {% No. We need to add corrections for the color stack...
        \@ifpackageloaded{color}%          ... but only if color.sty is loaded at all.
        {%
          \expandafter\def\expandafter\shipout@hook@TP\expandafter% Extend \shipout hook ...
          {\shipout@hook@TP\clearcolorcorrections@TP}%              ... by a command to clear counter stack.
                                %
          \newcommand{\clearcolorcorrections@TP}%                          The counter stack is cleared...
          {%                                                               ... on all `final' shipouts.
            \ifshippingduplicate
             \else
              \gdef\colorcorrections@TP{\relax}%
            \fi
          }
                                
          % Pray to god all drivers will support the following hacks...

          % Save `original' definition of \set@color. Our redefinition of \reset@color needs to know which color is
          % being reset, so we add this as an argument. As it would be inconvenient to add a lot of tokens with
          % \aftergroup, we wrap everything in a control sequence.
          \expandafter\def\expandafter\o@set@color@TP\expandafter%
          {%
            \set@color%                                                This is the `real' original definition.
            \expandafter\aftergroup\csname\current@color\endcsname%    Add definition of \current@color.
            }%                                                        

          \let\o@reset@color@TP=\reset@color%                          Save original definition of \reset@color.

          % We need one command to `just push' a color on the stack. Pushing is done by \set@color in a driver-specific
          % way. But \set@color also creates an instance of \reset@color using \aftergroup. This instance is gobbled by
          % this hack, hopefully leaving only the driver-specific code to push a color. Of course, this will break
          % spectacularly if \set@color doesn't have the form {<do something>\aftergroup\reset@color}. 
          \def\remove@resetcolor@TP#1\aftergroup\reset@color%          
          {\def\pushcolor@TP##1{{\def\current@color{##1}#1}}}%
                                %
          \expandafter\remove@resetcolor@TP\set@color

          % \reset@color gets the color definition in the form of a control sequence (because of \aftergroup, see
          % above). We have to `unwrap' it before pushing.
          \def\pushcolorname@TP#1%
          {%
            \begingroup \escapechar\m@ne\xdef\@gtempa{\string#1}\endgroup% Get the coded tokens back (without \ ).
            \expandafter\pushcolor@TP\expandafter{\@gtempa}%               ... and execute push.
            }%

          % Our own definition of \set@color adds a \reset@color command for the color just set to \colorcorrections@TP.
          \def\set@color%           
          {%
            \o@set@color@TP%                                             `Original' definition of \set@color.
            \expandafter\@temptokena\expandafter{\colorcorrections@TP}%  Add \o@reset@color@TP command at the front
            \xdef\colorcorrections@TP{\noexpand\o@reset@color@TP\the\@temptokena}% ...  of \colorcorrections@TP.
            }

          \def\reset@color#1%                                            \reset@color now receives the name of the color.
          {%
            \expandafter\addpushtoccor@TP\colorcorrections@TP\@nil{#1}%  Add a push command for this color to the front
                                                                      %  of \colorcorrections@TP.
            \o@reset@color@TP%                                           `Original' definition of \reset@color.
            }%

          \def\addpushtoccor@TP#1#2\@nil#3%      Add a push command for some color to the front of \colorcorrections@TP.
          {%
            \ifx\o@reset@color@TP#1%             For efficiency, a push immediately followed by a reset cancel out.
              \gdef\colorcorrections@TP{#2}%
             \else
              \gdef\colorcorrections@TP{\pushcolorname@TP{#3}#1#2}% Otherwise, add the push to \colorcorrections@TP.
            \fi
            }%
          }% matches \@ifpackageloaded{color}
        {}% No changes needed if color.sty is not loaded.
        }% matches second argument of \ifthenelse{\boolean{pdf}}
      }% matches \@ifundefined{VTeXversion}
    {% Yes. Color stack fixing unnecessary.
      \PackageWarning{texpower}
      {vtex doesn't need color stack correction.\MessageBreak Option fixcolorstack disabled.}%
      }%
    }% matches \ifthenelse{\boolean{fixcolorstack@TP}}
  {}%
  }% matches \AtBeginDocument


%-----------------------------------------------------------------------------------------------------------------------
% Kernel functions for overloading \output.
% This is the `inner kernel' which lies behind all dynamic effects.

% Some user level parameters.

% This flag can be evaluated at \output (resp. \shipout) time and tells whether the page being shipped out is a
% duplicate page.
\newif\ifshippingduplicate% 

% The command used to shipout a duplicate page.
\providecommand{\TPeject}{\newpage}


% Some internal registers to store away things.

% Contents of the page so far. These have to be duplicated on every subpage.
\newbox\mempageconts@TP

% Footnotes on the page being duplicated. These have to be duplicated also.
\newinsert\memfootins@TP

% Original definition of output routine.
\newtoks\memoutput@TP


% Save current page contents to a box.

% Which counters are to be restored to their original value after \pause?
\def\cl@@ckptpause@TP{\@elt{page}}

% Save values of counters from \cl@@ckptpause@TP so that they can be restored with \restorepausecounters@TP.
\def\savepausecounters@TP{%
  \begingroup
    \def\@elt##1{\global\csname c@##1\endcsname\the\csname c@##1\endcsname}%
    \xdef\restorepausecounters@TP{\cl@@ckptpause@TP}%
  \endgroup
  }

% User-level command to add a counter name to \cl@@ckptpause@TP.
\newcommand{\pausesafecounter}[1]%
{\expandafter\def\expandafter\cl@@ckptpause@TP\expandafter{\cl@@ckptpause@TP\@elt{#1}}}

% Save the current page contents to the box \mempageconts@TP by overloading and triggering \output. Footnotes are also
% saved. The saved page contents are used by \pause and all \stepwise variants for making duplicates of page contents.
\def\save@TP
{%
  \par%                                                Always end current paragraph.
  \global\setbox\mempageconts@TP=\copy\voidb@x%        Initialise \mempageconts@TP (suggested by Ross Moore).
  \savepausecounters@TP%                               Save counters.
  \memoutput@TP=\output%                               Make backup copy of output routine.
  \output={\global\setbox\mempageconts@TP=\box\@cclv}% Copy current page contents.
  \eject%                                              Trigger now.
  \global\setbox\memfootins@TP=\copy\footins%          Save footnotes.
  \global\skip\memfootins@TP=\skip\footins
  \global\count\memfootins@TP=\count\footins
  \global\dimen\memfootins@TP=\dimen\footins
  \output=\memoutput@TP%                               Restore output routine.
  }

%-----------------------------------------------------------------------------------------------------------------------
% Kernel functions for re-inserting page contents.
% Used by \pause and also by variants of \stepwise.

% Filter file and anchor whatsits out of a duplicate page. Called by \shipout@hook@TP. Does nothing by default.
\let\filterpage@TP\relax

% Interpretation of \filterpage@TP for duplicate pages. Assigned by \outputduplicate@TP.
\newcommand{\filterwhatsits@TP}{\global\setbox\@cclv=\hbox{\leaders\copy\@cclv\hskip\wd\@cclv}}

% Insert saved page contents for the first time.
\newcommand{\insertfirstduplicate@TP}
{\unvcopy\mempageconts@TP}%             Just output the vbox's contents.

% Execute color correction stack accumulated when the fixcolor option is given.
\newcommand{\do@colorcorrections@TP}
{%
  {%
    \colorcorrections@TP%               Execute color correction stack.
    \gdef\colorcorrections@TP{\relax}%  Re-initialize for next round.
    }%
  }

% Insert saved page contents for the second time (and all further times).
\newcommand{\insertsecondduplicate@TP}
{%
  \do@colorcorrections@TP%                         Execute color correction stack.
  \global\setbox\footins=\copy\memfootins@TP%      Restore footnotes.
  \global\skip\footins=\skip\memfootins@TP
  \global\count\footins=\count\memfootins@TP
  \global\dimen\footins=\dimen\memfootins@TP
  \unvcopy\mempageconts@TP%                        Output the vbox's contents.
  }

% Ship out a duplicated page.
\newcommand{\outputduplicate@TP}
{%
  \shippingduplicatetrue%                       This switch can be evaluated in panels or headers/footers.
  \global\let\filterpage@TP\filterwhatsits@TP%  Filter out file whatsits when shipping out.
  \global\let\o@hyper@@anchor@TP\hyper@@anchor% Save definition of hyperref command for hyper anchors.
  \global\let\hyper@@anchor\@gobble%            Disable hyper anchors on duplicate pages to avoid duplicate page anchors.
  \TPeject%                                     Shipout page.
  \global\let\hyper@@anchor\o@hyper@@anchor@TP% Restore definition of hyperref command for hyper anchors.
  \global\let\filterpage@TP\relax%              Disable whatsit filtering.
  \shippingduplicatefalse%                      Unset switch.
  }%


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of \pause.
% 
% \pause ends the current paragraph, ships out the current page, starts a new page and copies whatever was on the
% current page onto the new page, where typesetting is resumed. This will create the effect of a `pause' in the
% presentation, i.e. the presentation stops because the current page ends at the point where the \pause command occurred
% and is resumed at this point when the presenter switches to the next page.
%

\providecommand\pause% If pause.sty is loaded, the existing definition of \pause is not overwritten.
{%
  \save@TP%                                         Save contents of the page...
  \insertfirstduplicate@TP%                         ... and insert again.
  \ifthenelse{\boolean{display}}%                   Are dynamic features enabled?
  {% Yes.
    \outputduplicate@TP%                            Output page.
    \restorepausecounters@TP%                       Restore counters (page number).
    \insertsecondduplicate@TP%                      Reinsert saved contents.
    }
  {}%
  }%


%=======================================================================================================================
% The central part of this package, implementing \stepwise and all functions surrounding it.
%
% General usage: \stepwise{<contents>}
%
% As of itself, \stepwise doesn't do very much. If <contents> contains one or more constructs of the form
% \step{<stepcontents>}, the following happens: 
%
% 1. The current paragraph is ended.
%
% 2. The current contents of the page are saved (as with \pause).
%
% 3. As many pages as there are \step commands in <contents> are produced.
%    Every page starts with what was on the current page when \stepwise started.
%    The first page also contains everything in <contents> which is not in <stepcontents> for any \step command. 
%    The second page additionally contains the <stepcontents> for the first \step command, and so on, until all
%    <stepcontents> are displayed. 
%
% 4. When all <stepcontents> are displayed, \stepwise ends and typesetting is resumed (still on the current page). 
%  
% This will create the effect that the \step commands are executed `step by step'.
%
% For a more detailed description of \stepwise, \step and their options, see below.

% Most of the registers, macros and environments defined in the following are part of the user interface, so no @s.

%-----------------------------------------------------------------------------------------------------------------------
% Registers.
%

\newcounter{totalsteps}           % The total number of \step commands occurring in <contents>.

\newcounter{firststep}            % The number at which the counter step starts counting. Can be set in the optional
                                  % argument of \stepwise.

\newcounter{step}                 % The number of the step currently being performed.

\newcounter{stepcommand}          % The number of the current \step command (only useful inside <stepcontents>).

\newcounter{stepsperformed}       % The total number of \step commands which have been activated so far (this can differ
                                  % from \value{step} if the order of \step commands is changed via the optional
                                  % argument of \step).

\newboolean{firstactivation}      % Is this \step command currently active for the first time? (only useful inside
                                  % <stepcontents>).

\newboolean{active}               % Is this \step command currently active? (only useful inside <stepcontents>).


%-----------------------------------------------------------------------------------------------------------------------
% Custom commands for displaying <stepcontents>. Some of them are selected by the switches \boxedsteps and
% \nonboxedsteps.  

% Display <stepcontents> in a box.
\newcommand{\displayboxed}        
{%
  \ifmmode                                           % We need to distinguish between math and text mode.
    \expandafter\mathpalette\expandafter\math@db@TP  % In math mode, the style has to be respected.
  \else
    \expandafter\text@db@TP
  \fi
}
\newcommand{\text@db@TP}[1]{\mbox{#1}}            % In text mode, we just use an \mbox.
\newcommand{\math@db@TP}[2]{\mbox{$\m@th#1{#2}$}} % In math mode, the style (#1) is inserted by \mathpalette.


% Display <stepcontents> `as is'.
\let\displayidentical=\@iden      


%-----------------------------------------------------------------------------------------------------------------------
% Custom commands for `hiding' \stepcontents at the time the corresponding \step is not active.
% Hiding stuff is not as easy as it seems...
% Often, it is desirable that an appropriate amount of `space' is left where something is hidden, in case something
% visible follows or the hidden stuff is part of an alignment structure. Even if this is not the case, completely
% ignoring hidden text containing further \step's can disturb the accounting of \stepwise, because \step numbers become
% unaligned.
% On the other hand, a lot of things which might be hidden (solitary &'s if the hidden text is part of an alignment
% structure, for instance) execute an implicit group closing and don't like it at all to be enclosed in boxes, for
% instance.
% Because of these conflicting constraints, several methods for hiding content are provided. It is up to the user to
% select the one most appropriate for each type of content, or to use the suggestions below as inspiration for own
% definitions. 

% Hide <stepcontents>, but display an appropriate amount of white space in the form of an appropriately dimensioned,
% empty box.
\newcommand{\hidephantom}[1]      
{%
  {% a group makes redefinitions local
    \leavevmode\phantom{#1}%            % \phantom normally produces an \hbox. \leavevmode makes it behave like \mbox.
    }%
  }

% Ignore <stepcontents> completely.
\newcommand{\hideignore}[1]{}          

% Sometimes, ignoring <stepcontents> completely can lead to confusion of \stepwise's accounting when <stepcontents>
% contains further \step commands. \hidesmartignore produces no output, but executes <stepcontents> (in a box). Note
% that this will lead to errors if for instance <stepcontents> contains a tabular character & from an alignment
% structure. 
\newcommand{\hidesmartignore}[1]{\setbox\tempbox@TP=\vbox{#1}}

% The command \hidetext makes its argument `invisible', but without putting it into a box, thus preserving line
% breaks. 
% \hidetext needs the soul package to work. If it is not loaded, \hidetext is defined to be equal to \hideboxed.
% Because of restrictions implied by the soul package, \hidetext is quite picky about the `regularity' of its
% argument. That is, a lot of things will break when in the argument of \hidetext. See the documentation of the
% soul package for hints how to prevent this.
\AtBeginDocument%                               Just providing for the case that soul is loaded after texpower.
{%
  \@ifpackageloaded{soul}%                      Can we use the soul package?
  {%                                            
    \@ifpackagelater{soul}{2002/05/28}%         Correct version?
    {% Yes. Let's define the necessary macros.
      \DeclareRobustCommand*\hidetext
      {%
        \leavevmode%                              To prevent \phantom from inserting an hbox into the vertical list.
        \SOUL@setup
        \def\SOUL@everytoken{\phantom{\the\SOUL@token\SOUL@setkern\SOUL@charkern}}% Make current token `invisible'.
        \def\SOUL@everyhyphen
        {%
          \discretionary
          {%
            \unkern
            \phantom{\SOUL@setkern\SOUL@hyphkern\char\hyphenchar\font}%  Output an `invisible' hyphen if needed.
          }{}{}%
        }%
        \SOUL@%
      }%
    }%
    {% No. Encourage people to update.
      \PackageInfo{texpower}
      {Package soul too old.\MessageBreak Command \string\hidetext\space disabled}%
      \let\hidetext=\hidephantom%                 \hidephantom is a sorry excuse for \hidetext...
    }%
  }%
  {% No. In this case, there is no useful definition for \hidetext.
    \PackageInfo{texpower}
    {Package soul not loaded.\MessageBreak Command \string\hidetext\space disabled}%
    \let\hidetext=\hidephantom%                 \hidephantom is a sorry excuse for \hidetext...
  }%
}


% Helper command to switch to `dimmed' textcolor or mathcolor (if in math mode and colormath option is set).
\ifthenelse{\boolean{colormath@TP}}% Should we color math?
{% Yes.
  \newcommand{\commitcolor@TP}
  {\textcolor{\ifmmode mathcolor\else textcolor\fi}}% Switch to mathcolor if in math mode, to textcolor otherwise.
  }
{% No.
  \newcommand{\commitcolor@TP}{\textcolor{textcolor}}% Switch to textcolor.
}

% The command \hidedimmed doesn't really make its argument `invisible'. Instead, it dims all colors so the argument
% `fades' into the background.
\ifthenelse{\boolean{TPcolor}}%            Can we use colors at all?
{% Yes.
  \newcommand{\hidedimmed}[1]%             Make argument appear in `dimmed' colors.
  {%
    {% A group makes the color changes local.
      \ifthenelse{\boolean{instepwise@TP}}{\usecolorset{stwcolors}}{}% Just in case we currently are in dimmed mode...
      \dimcolors%          Dim colors.
      \commitcolor@TP{#1}% Switch on dimmed color.
      }%
    }%
  }
{\let\hidedimmed=\displayidentical}% No. Disable this command.


% The command \hidevanish makes its argument `invisible' by switching to the background color. Of course, this only
% works if the background is uniformly colored.
\ifthenelse{\boolean{TPcolor}}% Can we use colors at all?
{% Yes.
  \newcommand{\hidevanish}[1]%            Make argument `vanish' by changing colors.
  {\textcolor{\vanishcolor}{\vanishcolors#1}}
  }
{\let\hidevanish=\hidephantom}% No. Use \hidephantom instead.



%-----------------------------------------------------------------------------------------------------------------------
% The displaying and hiding of <stepcontents> is controlled by the commands \displaystepcontents and
% \hidestepcontents. The following switches define these to be either the boxed or the `as is' versions defined above.

\newcommand{\boxedsteps}          % Use boxed versions.
{\let\displaystepcontents=\displayboxed\let\hidestepcontents=\hidephantom}

\newcommand{\nonboxedsteps}       % Use nonboxed versions.
{\let\displaystepcontents=\displayidentical\let\hidestepcontents=\hideignore}

\nonboxedsteps                    % The default is to use the nonboxed versions. This can be changed in the optional
                                  % argument of \stepwise.


%-----------------------------------------------------------------------------------------------------------------------
% There is another command named \activatestep which controls what happens when a \step command is activated for the
% first time. This is defined to do nothing by default.

\let\activatestep=\displayidentical


% The length \highlightboxsep gives the width of the frame around the box created by \highlightboxed.

\newlength{\highlightboxsep}
\setlength{\highlightboxsep}{.5\fboxsep}


% \highlightboxed{<text>} puts <text> into an \mbox with coloured background if the colorhighlight option is set, and
% into an \fbox otherwise. As this is meant as an interpretation of \activatestep, it is made sure that the resulting
% box has the same dimensions as the argument (the outer frame may overlap surrounding text). 
\DeclareRobustCommand{\highlightboxed}
{%
  \ifmmode%                                           Check for math mode.
    \expandafter\mathpalette\expandafter\math@hb@TP%  Math mode version needs to respect current style.
  \else
    \expandafter\text@hb@TP%                          Text mode version.            
  \fi
}

\newcommand{\math@hb@TP}[2]{\text@hb@TP{$\m@th#1{#2}$}}% Math mode version of \highlightboxed.

% The text mode version of \highlightboxed does the `real' work.
\ifthenelse{\boolean{colorhighlight@TP}}%                  Color highlighting enabled?
{%  Yes; use a box with colored background.
  \newcommand{\text@hb@TP}[1]
  {%
    \makebox[\width-2\highlightboxsep]%                    Make the frame stick out at the sides.
    {%
      \setlength{\fboxsep}{\highlightboxsep}%              Set frame size.
      \raisebox{0pt}[\height-\fboxsep][\depth-\fboxsep]%   Make the frame stick out above and below.
      {\colorbox{highlightcolor}{#1}}%                     Make colored box containing <text>.
      }%
    }%
  }% matches \ifthenelse{\boolean{colorhighlight@TP}}
{%  No; use an \fbox.
  \newcommand{\text@hb@TP}[1]
  {%
    \makebox[\width-2\highlightboxsep-2\fboxrule]%         Make the frame stick out at the sides.
    {%
      \setlength{\fboxsep}{\highlightboxsep}%              Set frame size.
      \raisebox{0pt}[\height-\fboxsep-\fboxrule][\depth-\fboxsep-\fboxrule]% Make the frame stick out above and below.
      {\fbox{#1}}%%                                        Make an fbox containing <text>.
      }%
    }%
  }% matches second argument of \ifthenelse{\boolean{colorhighlight@TP}}


% \highlighttext is the counterpart of \highlightboxed for arbitrary text. It puts its argument on a colored background
% without putting it into a box (i.e. line breaks and hyphenation still work) if the colorhighlight option is set, and
% underlines otherwise. As this is meant as an interpretation of \activatestep, it is made sure that the resulting text
% has the same dimensions as the argument (the outer frame may overlap surrounding text).
% \highlighttext needs the soul package to work. If it is not loaded, \highlighttext is defined to do nothing.
% Because of restrictions implied by the soul package, \highlighttext is quite picky about the `regularity' of its
% argument. That is, a lot of things will break when in the argument of \highlighttext. See the documentation of the
% soul package for hints how to prevent this.

 \AtBeginDocument%                               Just providing for the case that soul is loaded after texpower.
 {%
   \@ifpackageloaded{soul}%                      Can we use the soul package?
   {%                                            
     \@ifpackagelater{soul}{2002/05/28}%         Correct version?
     {% Yes. Let's define the necessary macros.
       \ifthenelse{\boolean{colorhighlight@TP}}%         Color highlighting enabled?
       {%  Yes; use a colored background.
        %  This is implemented as an application of soul (modifying the code for underline). See the documentation of the
        %  soul package for details on soul.
         \newlength{\SOUL@boxheight@TP}%                 Height of colored patch.
         \newlength{\SOUL@boxtotalheight@TP}%            Total height of colored patch.
         \newlength{\SOUL@boxdepth@TP}%                  Depth of colored patch.
         \DeclareRobustCommand*\highlighttext
         {%
           \leavevmode%                                  To prevent \smash from inserting an hbox into the vertical list.
           \SOUL@ulsetup%                                Underline initialization.
           \def\SOUL@preamble
           {%
             \setlength{\SOUL@boxdepth@TP}%                  \SOUL@uldepth is below the depth of any letter.
             {\SOUL@uldepth+\highlightboxsep}%
             \def\SOUL@uldepth{-\SOUL@boxheight@TP}%         For correctly positioning the rule.
             \setlength{\SOUL@boxheight@TP}{\heightof{/}+\highlightboxsep}%             Calculate `good' height.
             \setlength{\SOUL@boxtotalheight@TP}{\SOUL@boxdepth@TP+\SOUL@boxheight@TP}% Calculate total height.
             \def\SOUL@ulthickness{\SOUL@boxtotalheight@TP}% The thickness of the rule is the total height of the box.
             \smash%                                         Make the left border of the colored patch.
             {%
               \llap{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{\highlightboxsep}{\SOUL@boxtotalheight@TP}}%
             }%
             \SOUL@ulpreamble%                               Underline preamble.
           }%
           \def\SOUL@everytoken
           {%
             {%
               \setbox\tempbox@TP\hbox{\the\SOUL@token\SOUL@setkern\SOUL@charkern}%
               \dimen@ii\wd\tempbox@TP
               \smash{\rlap{\color{highlightcolor}\SOUL@ulleaders\hskip\dimen@ii}}%
               \unhbox\tempbox@TP%
               \smash{\rlap{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{\highlightboxsep}{\SOUL@boxtotalheight@TP}}}%
             }%
           }%
           \def\SOUL@everyspace
           {%
             \cleaders\hbox{\smash{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{1pt}{\SOUL@boxtotalheight@TP}}}%
             \hskip\spaceskip
             \smash{\llap{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{\highlightboxsep}{\SOUL@boxtotalheight@TP}}}%
           }%
           \def\SOUL@everyhyphen
           {%
             \discretionary
             {\unkern
             \setbox4\hbox{\SOUL@setkern\SOUL@hyphkern\char\hyphenchar\font}%
             \smash{\rlap{\color{highlightcolor}\SOUL@ulleaders\hskip\wd4}}%
             \box4%
             \smash{\rlap{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{\highlightboxsep}{\SOUL@boxtotalheight@TP}}}%
             }%
           {\smash{\llap{\color{highlightcolor}\rule[-\SOUL@boxdepth@TP]{\highlightboxsep}{\SOUL@boxtotalheight@TP}}}}%
           {}%
           }%
           \let\SOUL@everysyllable\empty
         \SOUL@%
         }%
       }% matches \ifthenelse{\boolean{colorhighlight@TP}}%
     {% No. Underline.
       \DeclareRobustCommand*\highlighttext
       {%
         \SOUL@ulsetup%                        We modify SOUL's standard definition of underlining, making sure
         \def\SOUL@everysyllable%                 the result uses no more space than the non-underlined text.
         {%
           {%
             \let\o@rlap@TP=\rlap
             \def\rlap####1{\setbox\@tempboxa\box\z@\smash{\o@rlap@TP{####1}}\setbox\z@\box\@tempboxa}%
             \SOUL@uleverysyllable
             }%
           }%
         \def\SOUL@everyspace
         {\cleaders\hbox{\smash{\vrule\@depth\SOUL@uldp\@height\SOUL@ulht\@width.5pt}}\hskip\spaceskip}%
         \def\SOUL@everyhyphen{\discretionary
           {\unkern
             \setbox4\hbox{\SOUL@setkern\SOUL@hyphkern\char\hyphenchar\font}%
             \smash{\rlap{\SOUL@ulleaders\hskip\wd4}\box4}}{}%
           {}}%
         \SOUL@%
         }%
       }% matches second argument of \ifthenelse{\boolean{colorhighlight@TP}}%
     }%
     {% No. Encourage people to update.
       \PackageInfo{texpower}
       {Package soul too old.\MessageBreak Command \string\highlighttext\space disabled}%
       \let\highlighttext=\@iden%                 
     }%
   }% matches \@ifpackageloaded{soul}
   {% No. In this case, there is no useful definition for \highlighttext.
     \PackageWarning{texpower}
     {Package soul not loaded.\MessageBreak Command \string\highlighttext\space disabled}%
     \let\highlighttext=\@iden
     }% matches second argument of \@ifpackageloaded{soul}
   }% matches \AtBeginDocument% 


% The command \highlightenhanced enhances all colors so the argument `stands out'.
\ifthenelse{\boolean{TPcolor}}% Can we use colors at all?
{% Yes.
  \newcommand{\highlightenhanced}[1]%             Make argument appear in `enhanced' colors.
  {%
    {% A group makes the color changes local.
      \ifthenelse{\boolean{instepwise@TP}}{\usecolorset{stwcolors}}{}% Just in case we currently are in enhanced mode...
      \enhancecolors%          Enhance colors.
      \commitcolor@TP{#1}%     Switch on enhanced color.
      }%
    }%
  }
{\let\highlightenhanced=\displayidentical}% No. Disable this command.


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of \step, \switch and relatives.
%
% \step takes two optional arguments for influencing the mode of activation, like this:
%
% \step[<activatefirst>][<whenactive>]{<stepcontents>}
%
% Both <activatefirst> and <whenactive> should be conditions in the syntax of the \ifthenelse command.
%
% <activatefirst> checks whether this \step is to be activated for the first time. The default value is
% \value{step}=\value{stepcommand}. By using \value{step}=<n>, this \step can be forced to appear as the n'th one.  
%  
% <whenactive> checks whether this \step is to be considered active at all. The default behaviour is to check whether
% this \step has been activated before (this is saved internally for every step).  
%  
% Both optional arguments allow two syntctical forms: 
%
% 1. enclosed in square brackets [...] like explained above.
%
% 2. enclosed in braces (...). In this case, <activatefirst> and <whenactive> are not treated as conditions in the sense
% of \ifthenelse, but as conditionals like those used internally by \LaTeX. That means, <activatefirst> (when enclosed
% in braces) can contain arbitrary \TeX code which then takes two arguments and expands to one of them, depending on
% whether the condition is fulfilled or not fulfilled. For instance, \step[<activatefirst>]{<stepcontents>} could be
% replaced by \step(\ifthenelse{<activatefirst>}){<stepcontents>}. 
%
% Internally, the default for the treatment of <whenactive> is (\if@first@TP@true), where \if@first@TP@true is an
% internal condition checking whether this \step has been activated before.  
%
% If you wish to give the second optional argument but not the first, just write \step[][<whenactive>]...
%
% There are the following variants of \step. In all cases, the treatment of optional arguments for controlling
% activation are the same as for \step: 
%
% \bstep[<activatefirst>][<whenactive>]{<stepcontents>}    Like \step, but is always boxed.
%                                                      
% \switch[<activatefirst>][<whenactive>]{<from>}{<to>}     Instead of hiding and displaying <stepcontents>, switch from
%                                                          <from> to <to>.
%                                                          
% \vstep[<activatefirst>][<whenactive>]                    Doesn't take an argument, but switches to `invisible' color.
%
% \dstep[<activatefirst>][<whenactive>]                    Doesn't take an argument, but switches to dimmed colors.
%
% \steponce[<activatefirst>]{<stepcontents>}               Like \step, but goes inactive again in the subsequent step.
%
% The following variants act like their counterparts, but appear at the same time as the previous \step (or variant).
%                                                          
% \restep[<activatefirst>][<whenactive>]{<stepcontents>}
%                                                      
% \rebstep[<activatefirst>][<whenactive>]{<stepcontents>}
%                                                      
% \reswitch[<activatefirst>][<whenactive>]{<from>}{<to>}
%                                                      
% \revstep[<activatefirst>][<whenactive>] 
%
% \redstep[<activatefirst>][<whenactive>]


% Optional argument handling.

% \pickup@s@optargs@TP reads the optional arguments of \step (or \switch, or relatives) and then calls \@do@s@TP.
\newcommand{\pickup@s@optargs@TP}
{%
  \@ifnextchar[%]            Check for first optional argument in [...] syntax.
  {\f@brackstep@TP}%
  {%
    \@ifnextchar(%)          Check for first optional argument in (...) syntax.
    {\f@parenstep@TP}
    {\f@brackstep@TP[]}%     No optional argument given; call with empty argument in [...] syntax (default).
    }%
}

\def\f@brackstep@TP[#1]%     First optional argument was given in [...] syntax.
{%
  \def\tmp@TP{#1}%
  \ifx\tmp@TP\empty%         Optional argument empty?
    \def\f@step@TPcheck{\ifthenelse{\value{step}=\value{stepcommand}}}% Yes; use default.
   \else
    \def\f@step@TPcheck{\ifthenelse{#1}}% No; condition is defined via \ifthenelse.
  \fi
  \f@step@TP%                Go on and check for second optional argument.
}

\def\f@parenstep@TP(#1)%     First optional argument was given in (...) syntax.
{%
  \def\f@step@TPcheck{#1}%   Save condition (given as argument).
  \f@step@TP%                Go on and check for second optional argument.
  }

\newcommand{\f@step@TP}%     Pick up the second optional argument.
{%
  \@ifnextchar[%]            Check for second optional argument in [...] syntax.                       
  {\s@brackstep@TP}
  {%
    \@ifnextchar(%)          Check for second optional argument in (...) syntax.                 
    {\s@parenstep@TP}
    {\s@parenstep@TP(\if@first@TP@true)}% No second optional argument given;
    }%                                    call with \if@first@TP@true in (...) syntax (default).
}

\def\s@brackstep@TP[#1]%     Second optional argument was given in [...] syntax.
{%
  \def\s@step@TPcheck{\ifthenelse{#1}}% Condition is defined via \ifthenelse.
  \@do@s@TP%                Go on. 
  }

\def\s@parenstep@TP(#1)%     Second optional argument was given in (...) syntax.
{%
  \def\s@step@TPcheck{#1}%   Save condition (given as argument).
  \@do@s@TP%                Go on.
  }


% The following are needed to switch between the `switch behaviour' and the `step behaviour' of \@@switch@TP, which
% implements the functionality of both \switch and \step.

\newcommand{\deactivate@inner@TP}% \switch behaviour.
{%
  \let\inner@display@TP=\displayidentical% Both \inner@display@TP and \inner@hide@TP just expand to their argument.
  \let\inner@hide@TP=\displayidentical%
  }

\newcommand{\activate@inner@TP}% \step behaviour.
{%
  \let\inner@display@TP=\displaystepcontents% Use the user interface macros \displaystepcontents and \hidestepcontents.
  \let\inner@hide@TP=\hidestepcontents%
  }

% Implementation of \step.

% \proper@step@TP is the `real' implementation of \step. Most of the time, \step is defined to execute
% \proper@step@TP.
\newcommand{\proper@step@TP}{\let\@do@s@TP=\@step@TP\pickup@s@optargs@TP}


% \@step@TP implements the functionality of \step by calling \@@switch@TP, which points to \@switch@TP most of the time.
\newcommand{\@step@TP}[1]{\activate@inner@TP\@@switch@TP{#1}{#1}}

% Inside, \@step@TP executes \@@switch@TP, which is the implementation of the \switch command (see below).

% Implementation of \switch.
%
% \switch works exactly like \step, but it takes _two_ mandatory arguments and selects the first if `not active', the
% second if `active'.

% \proper@switch@TP is the `real' implementation of \switch. Most of the time, \switch is defined to execute
% \proper@switch@TP.
\newcommand{\proper@switch@TP}{\deactivate@inner@TP\let\@do@s@TP=\@@switch@TP\pickup@s@optargs@TP}

% \if@first@TP@true checks whether the \switch command number \value{stepcommand} has already been activated in this
% \stepwise session and selects one of its arguments accordingly. 
\newcommand{\if@first@TP@true}[2]% 
{%                                
  \expandafter                   % \first@TP@<n> is set to \@undefined if \switch command number <n> has not yet been
  \ifx\csname first@TP@\the\c@stepcommand\endcsname\empty%                            activated and \empty otherwise.
    #1%
   \else
    #2%
  \fi
  }

% \switch shouldn't change the status quo in AMSLaTeX's measuring pass in typesetting aligned formulae. To guarantee
% this, we check whether AMSLaTeX is measuring with AMSLaTeX's \ifmeasuring@. When AMSLaTeX is not loaded, we provide
% this check ourselves. 
\@ifundefined{ifmeasuring@}{\newif\ifmeasuring@}{}


% \@switch@TP implements the functionality of \switch. Most of the time, \@@switch@TP (which is called after checking for
% optional arguments) is defined to execute \@switch@TP.
\newcommand{\@switch@TP}[2]
{%
  \global\advance\c@stepcommand by 1\relax% This execution of \switch is counted.
  %
  % If the verbose option is set, type out some accounting information which can be used for debugging. 
  \ifthenelse{\boolean{verbose@TP}}
  {%
    \PackageInfo{texpower}
    {Step: \the\c@step, Stepcommand: \the\c@stepcommand,\MessageBreak Stepsperformed: \the\c@stepsperformed}%
    }
  {}%
  %
  \f@step@TPcheck% Is this step to be activated? \f@step@TPcheck is defined by the first optional argument of \switch.
  {% Yes.
    \if@first@TP@true{}% For non-unique conditions given as optional argument or when \reswitch is used, it might happen
    {%       that \first@TP@\value{stepcommand} is already set. In this case, don't advance the counter stepsperformed.
      \ifmeasuring@\else% Do nothing in AMSLaTeX's measuring pass for aligned equations.
        \global\expandafter\let\csname first@TP@\the\c@stepcommand\endcsname=\empty% Set \first@TP@\value{stepcommand}
      \fi
      \global\advance\c@stepsperformed by 1\relax% Advance the counter for `real' first activations.
      \gdef\current@step@TP{#2}%
      }%
    \setboolean{firstactivation}{true}% This switch can be tested in <stepcontents>, but also in <whenactive>.
    }
  {% No.
    \setboolean{firstactivation}{false}% This switch can be tested in <stepcontents>, but also in <whenactive>.
    }% End of \f@step@TPcheck
  %
  \let\o@afterstep@TP=\afterstep% We need to save the current definition of \afterstep.
  %
  \s@step@TPcheck% Is this step active? \s@step@TPcheck is defined by the second optional argument of \switch.
  {% Yes.
    \setboolean{active}{true}%               Make this fact known to the user.
    \ifthenelse{\boolean{firstactivation}}
    {\inner@display@TP{\activatestep{#2}}}%  `First' display of <stepcontents>.
    {\inner@display@TP{#2}}%                 Display <stepcontents>.
    }
  {% No.
    \setboolean{active}{false}%              Make this fact known to the user.
    \let\afterstep=\@gobble%                 Don't execute \afterstep here.
    \ifthenelse{\boolean{firstactivation}}
    {\inner@hide@TP{\activatestep{#1}}}%     Hide <stepcontents>, but with `first activation'.
    {\inner@hide@TP{#1}}%                    Hide <stepcontents>.
    }% End of \s@step@TPcheck
  %
  \let\afterstep=\o@afterstep@TP%            Restore the definition of \afterstep.
  }% End of the definition of \@switch@TP.


%-----------------------------------------------------------------------------------------------------------------------
% \restep is identical with \step, but is displayed at the same time as the previous \step.

\newcommand{\restep}
{%
  \global\advance\c@stepcommand by -1% This is done by simply counting \value{stepcommand} backwards.
  \proper@step@TP%                     Go on with \step.
  }

%-----------------------------------------------------------------------------------------------------------------------
% \reswitch is identical with \switch, but is displayed at the same time as the previous \switch.

\newcommand{\reswitch}
{%
  \global\advance\c@stepcommand by -1% This is done by simply counting \value{stepcommand} backwards.
  \proper@switch@TP%                     Go on with \switch.
  }


%-----------------------------------------------------------------------------------------------------------------------
% \bstep is a variant of \step which is always boxed.

\newcommand{\proper@bstep@TP}{\let\@do@s@TP=\@bstep@TP\pickup@s@optargs@TP}

% \@bstep@TP implements the functionality of \bstep by calling \boxedsteps and \@step@TP.

\newcommand{\@bstep@TP}[1]{{\boxedsteps\@step@TP{#1}}}

%-----------------------------------------------------------------------------------------------------------------------
% \rebstep is identical with \bstep, but is displayed at the same time as the previous \bstep.

\newcommand{\rebstep}
{%
  \global\advance\c@stepcommand by -1% This is done by simply counting \value{stepcommand} backwards.
  \proper@bstep@TP%                     Go on with \bstep.
  }


%-----------------------------------------------------------------------------------------------------------------------
% \dstep is a variant of \step which takes _no_ argument, but switches colors to `dimmed'.

% Helper command to switch to `dimmed' textcolor or mathcolor (if in math mode and colormath option is set).
\ifthenelse{\boolean{colormath@TP}}% Should we color math?
{% Yes.
  \newcommand{\commitcolors@TP}
  {\color{\ifmmode mathcolor\else textcolor\fi}}% Switch to mathcolor if in math mode, to textcolor otherwise.
  }
{% No.
  \newcommand{\commitcolors@TP}{\color{textcolor}}% Switch to textcolor.
}

\newcommand{\proper@dstep@TP}{\deactivate@inner@TP\let\@do@s@TP=\@dstep@TP\pickup@s@optargs@TP}

\ifthenelse{\boolean{TPcolor}}% Can we use colors at all?
{% Yes.
  \newcommand{\@dstep@TP}{\@@switch@TP{\dimcolors\commitcolors@TP}{\set@color}}
  }
{\newcommand{\@dstep@TP}{\@@switch@TP{}{}}}% No. Disable this command.

%-----------------------------------------------------------------------------------------------------------------------
% \redstep is identical with \dstep, but is displayed at the same time as the previous \dstep.

\newcommand{\redstep}
{%
  \global\advance\c@stepcommand by -1% This is done by simply counting \value{stepcommand} backwards.
  \proper@dstep@TP%                     Go on with \dstep.
  }

%-----------------------------------------------------------------------------------------------------------------------
% \vstep is a variant of \step which takes _no_ argument, but switches all colors to \vanishcolor.

\newcommand{\proper@vstep@TP}{\deactivate@inner@TP\let\@do@s@TP=\@vstep@TP\pickup@s@optargs@TP}

\ifthenelse{\boolean{TPcolor}}% Can we use colors at all?
{% Yes.
  \newcommand{\@vstep@TP}{\@@switch@TP{\vanishcolors\color{textcolor}}{\set@color}}
  }
{\newcommand{\@vstep@TP}{\@@switch@TP{}{}}}% No. Disable this command.

%-----------------------------------------------------------------------------------------------------------------------
% \revstep is identical with \vstep, but is displayed at the same time as the previous \vstep.

\newcommand{\revstep}
{%
  \global\advance\c@stepcommand by -1% This is done by simply counting \value{stepcommand} backwards.
  \proper@vstep@TP%                     Go on with \vstep.
  }

%-----------------------------------------------------------------------------------------------------------------------
% \steponce[<activatefirst>]{<stepcontents>} is a variant of \step which is active only at the time of activation and
% goes inactive again in the subsequent step.

\newcommand{\steponce}
{\@ifnextchar[{\brack@steponce@TP}{\@steponce@TP}}% Optional argument in square brackets?

\newcommand{\@steponce@TP}
{%
  \@ifnextchar(%%          Optional argument in parentheses?
  {\paren@steponce@TP}%
  {\brack@steponce@TP[]}%  [] is the default if no optional argument is given.
  }

\def\brack@steponce@TP[#1]%
{%
  \def\optarg@so@TP{[#1]}% Store optional argument for later re-insertion.
  \@@steponce@TP%          Proceed.
  }%

\def\paren@steponce@TP(#1){\def\optarg@so@TP{(#1)}\@@steponce@TP}

% Main body of \steponce.
\newcommand{\@@steponce@TP}[1]{\expandafter\step\optarg@so@TP[\boolean{firstactivation}]{#1}}


%-----------------------------------------------------------------------------------------------------------------------
% \multistep*[<activatefirst>]{<n>}{<stepcontents>} is a shorthand macro for executing several steps successively. In
% fact, it would better be called \multiswitch, because its functionality is based on \switch, it only acts like a
% (simplified) \step command which is executed `several times'.
% \multistep[<activatefirst>]{<n>}{<stepcontents>} expands to a sequence of <n> commands of the form
%      \switch[<activatefirst>][\boolean{firstactivation}]{}{<stepcontents>}
% with the effect that <stepcontents> is executed <n> times at different iterations of \stepwise. Note that
% [<activatefirst>] can also have the form (<activatefirst>), as usual for \switch.
% Because of the second optional argument [\boolean{firstactivation}], only one instance of <stepcontents> is displayed
% at a time.
% Inside <stepcontents>, a counter substep can be evaluated which tells the number of the current instance.
% In the starred form, the optional argument [\boolean{firstactivation}] is left out for the very last instance, so the
% last instance of <stepcontents> stays visible.

% New counter for the number of the current substep.
\newcounter{substep}

% User interface for \multistep.
\newcommand{\multistep}
{%
  \let\ns@ms@TP=\normalstep@ms@TP% Placeholder for `every step but the last one'.
  \let\nshook@ms@TP=\relax%        These hooks are used by \movie.
  \let\lshook@ms@TP=\relax
  \@ifstar%                        Starred version?
  {%
    \let\ls@ms@TP=\laststep@ms@TP% Last step acts differently.
    \multistep@TP%                 Collect optional argument and proceed.
    }
  {%
    \let\ls@ms@TP=\normalstep@ms@TP% Last step acts like all other steps.
    \multistep@TP%                   Collect optional argument and proceed.
    }%
  }

\newcommand{\multistep@TP}% Collect optional argument.
{\@ifnextchar[{\brack@multistep@TP}{\@multistep@TP}}% Optional argument in square brackets?

\newcommand{\@multistep@TP}
{%
  \@ifnextchar(%%          Optional argument in parentheses?
  {\paren@multistep@TP}%
  {\brack@multistep@TP[]}% [] is the default if no optional argument is given.
  }

\def\brack@multistep@TP[#1]%
{%
  \def\optarg@ms@TP{[#1]}% Store optional argument for later re-insertion.
  \@@multistep@TP%         Proceed.
  }%

\def\paren@multistep@TP(#1){\def\optarg@ms@TP{(#1)}\@@multistep@TP}

% Execute one step.
\newcommand{\normalstep@ms@TP}[1]
{%
  \expandafter\switch\optarg@ms@TP%  Re-insert optional argument.
  [\boolean{firstactivation}]{}{#1}% `normal' steps appear only once.
  }

\newcommand{\laststep@ms@TP}[1]
{\expandafter\switch\optarg@ms@TP{}{#1}}% In the starred version, the last step doesn't disappear.

% Main body of \multistep.
\newcommand{\@@multistep@TP}[2]
{%
  \setcounter{substep}{0}%       Initialize substep counter.
  \whiledo{\value{substep}<#1}%  Iterate <n> times.
  {%
    \stepcounter{substep}%
    \ifthenelse{\value{substep}=#1}% Last step?
    {\ls@ms@TP{\lshook@ms@TP#2}}%    Execute single step (together with \movie hooks).
    {\ns@ms@TP{\nshook@ms@TP#2}}%
    }%
  }



% \movie*[<activatefirst>]{<n>}{<dur>}[<stop>]{<stepcontents>} works like \multistep, but between \steps, pages are
% advanced automatically every <dur> seconds.
% The additional optional argument <stop> gives the code (default: \stopAdvancing) which stops the animation. 

% User interface for \movie.
\newcommand{\movie}
{%
  \let\ns@ms@TP=\normalstep@ms@TP% Placeholder for `every step but the last one'.
  \def\nshook@ms@TP{\afterstep{\pageDuration{\dur@ms@TP}}}% Page duration to be used between steps.
  \def\lshook@ms@TP{\afterstep{\end@ms@TP}}%                Page duration setting after last step.
  \@ifstar%                        Starred version?
  {%
    \let\ls@ms@TP=\laststep@ms@TP% Last step acts differently.
    \movie@TP%                     Collect optional argument and proceed.
    }
  {%
    \let\ls@ms@TP=\normalstep@ms@TP% Last step acts like all other steps.
    \movie@TP%                       Collect optional argument and proceed.
    }%
  }

\newcommand{\movie@TP}% Collect optional argument.
{\@ifnextchar[{\brack@movie@TP}{\@movie@TP}}%        Optional argument in square brackets?

\newcommand{\@movie@TP}
{\@ifnextchar({\paren@movie@TP}{\brack@movie@TP[]}}% Optional argument in parentheses?

\def\brack@movie@TP[#1]{\def\optarg@ms@TP{[#1]}\@@movie@TP}% Store optional argument and proceed.
\def\paren@movie@TP(#1){\def\optarg@ms@TP{(#1)}\@@movie@TP}

\newcommand{\@@movie@TP}[2]% Collect <n> and <dur> arguments.
{\gdef\dur@ms@TP{#2}\gdef\nosteps@ms@TP{#1}\@@@movie@TP}

\newcommand{\@@@movie@TP}[1][\stopAdvancing]% Collect second optional argument and call body of \multistep.
{\gdef\end@ms@TP{#1}\@@multistep@TP{\nosteps@ms@TP}}


% \overlays[<activatefirst>]{<n>}{<stepcontents>} is another shorthand macro for executing several steps
% successively. In contrast to \multistep, it doesn't print things _after_ each other, but _over_ each other. Obviously,
% there is no need for a starred version.
% \overlays[<activatefirst>]{<n>}{<stepcontents>} expands to a sequence of <n> commands of the form
%      \switch[<activatefirst>]{}{\rlap{<stepcontents>}}
% with the effect that <stepcontents> is executed <n> times at different iterations of \stepwise, and all results are
% overlaid over each other. Note that [<activatefirst>] can also have the form (<activatefirst>), as usual for \switch.
% Inside <stepcontents>, a counter substep can be evaluated which tells the number of the current instance.

% User interface for \overlays.
\providecommand{\overlays}
{\@ifnextchar[{\brack@overlays@TP}{\@overlays@TP}}% Optional argument in square brackets?

\newcommand{\@overlays@TP}
{%
  \@ifnextchar(%%          Optional argument in parentheses?
  {\paren@overlays@TP}%
  {\brack@overlays@TP[]}%  [] is the default if no optional argument is given.
  }

\def\brack@overlays@TP[#1]%
{%
  \def\optarg@ov@TP{[#1]}% Store optional argument for later re-insertion.
  \@@overlays@TP%          Proceed.
  }%

\def\paren@overlays@TP(#1){\def\optarg@ov@TP{(#1)}\@@overlays@TP}

% Main body of \overlays.
\newcommand{\@@overlays@TP}[2]
{%
  \setcounter{substep}{0}%       Initialize substep counter.
  \leavevmode%                   Make sure that \rlap doesn't insert anything in the vertical list.
  \whiledo{\value{substep}<#1}%  Iterate <n> times.
  {%
    \stepcounter{substep}%
    \expandafter\switch\optarg@ov@TP{}{\ifthenelse{\boolean{firstactivation}}{\mbox{#2}}{\rlap{#2}}}%
  }%
}


%-----------------------------------------------------------------------------------------------------------------------
% Implementation of \stepwise.
%
% Every variant of \stepwise takes an optional argument, like this
% 
% \stepwise[<settings>]{<contents>}
% 
% <settings> will be placed right before the internal loop which produces the sequence of pages.  It can contain
% settings of parameters which modify the behaviour of \stepwise or \step. <settings> is placed inside a group so all
% changes are local to this call of \stepwise. 
%
% Usually, the first page of a sequence produced contains only material which is not part of any <stepcontents>. The
% first <stepcontents> are displayed on the second page of the sequence. 
%
% For special effects, it might be desirable to have the first <stepcontents> active even on the first page of the
% sequence. 
%
% All variants of \stepwise have a starred version (e.\,g.\ \stepwise*) which does exactly that.


% When \stepwise is executed, for every page of the sequence generated, <contents> is wrapped in the environment
% stepcapsule (but not grouped by default). This is empty by default for minimum intrusion. Redefine stepcapsule in the
% optional argument of \stepwise to change this (as is done for instance by \liststepwise).

\newenvironment{stepcapsule}{}{}


% Because \step commands usually occur deep in some nested structure, it is difficult to set local parameters (like page
% transitions) only for certain steps (local settings executed in <stepcontents> would be undone by closing groups).
%
% \afterstep{<setting>} has the effect that <setting> will be performed _after_ the current execution of <contents>,
% right before the page break for this page of the sequence generated.

\newcommand{\afterstep}[1]
{%
  \gdef\@afterstep@TP{#1}% The argument is simply stored in \@afterstep@TP, which is executed in \stepwise.
  }


% One new counter for saving the value of firststep.
\newcounter{o@fs@TP}


% \stepwise user interface.
\newcommand{\stepwise}
{%
  \global\c@o@fs@TP=\c@firststep\relax%     Save the default value of counter firststep.
  \@ifstar%                                 Using the starred version?
  {% Yes.
    \c@firststep=1\relax%                   Start with counter step at number 1.
    \@stepwise@TP%                          Collect optional argument and proceed.
    }
  {% No.
    \@stepwise@TP%                          Use the default.
    }% End of \@ifstar.
  }%


% Sometimes, it might happen that vertical spacing is different on every page of a sequence generated by \stepwise,
% making lines `wobble'.  
% There are two custom versions \liststepwise, \parstepwise of \stepwise which produce better vertical spacing by
% putting an invisible rule before <contents>. This will almost certainly lead to `consistent' spacing which might
% nevertheless be different from the spacing if \liststepwise wasn't present.
% 
% \liststepwise{<contents>} works exactly like \stepwise, but <contents> is delimited by a rule of height zero. Use for
% list environments and aligned equations. 
% 
% \parstepwise{<contents>} works like \liststepwise, but \boxedsteps is turned on by default. Use for texts where \steps
% are to be filled into blank spaces. 
%

% Command to activate special stepcapsule for \liststepwise.
\newcommand{\list@stepcapsule}
{%
  \renewenvironment{stepcapsule}%                    stepcapsule is to put an invisible rule on the vertical list.
  {\vspace*{\parskip}\hrule \@height\z@\relax}{}
  }%

\let\par@stepcapsule=\list@stepcapsule%              Identical for \parstepwise.


% User interface for \liststepwise.
\newcommand{\liststepwise}
{%
  \@ifstar%                           Starred version? 
  {\def\star@TP{*}\@liststepwise@TP}% Save star in \star@TP, collect optional argument and proceed.
  {\def\star@TP{}\@liststepwise@TP}%  Collect optional argument and proceed (non-starred version).
  }

\newcommand{\@liststepwise@TP}[1][]%  Collect optional argument.
{%
  \expandafter\stepwise\star@TP%                             Re-insert the star (if given).
  [%
    \list@stepcapsule%                                       Activate special stepcapsule.
    #1%                                                      Insert optional argument of \liststepwise.
    ]%
  }

% User interface for \parstepwise.
\newcommand{\parstepwise}
{%
  \@ifstar%                           Starred version? 
  {\def\star@TP{*}\@parstepwise@TP}%  Save star in \star@TP, collect optional argument and proceed.
  {\def\star@TP{}\@parstepwise@TP}%   Collect optional argument and proceed (non-starred version).
  }

\newcommand{\@parstepwise@TP}[1][]%  Collect optional argument.
{%
  \expandafter\stepwise\star@TP%     Re-insert the star (if given).
  [%
    \boxedsteps%                     Activate \boxedsteps.
    \par@stepcapsule%                Activate special stepcapsule.
    #1%                              Insert optional argument of \parstepwise.
    ]%
  }


% \count@em@TP is used by \stepwise as a redefinition of \@@switch@TP for counting \step commands.
\newcommand{\count@em@TP}[2]
{%
  \global\advance\c@stepcommand by 1\relax% We simply advance the number of \step commands...
  #2%                                     ... and execute the second argument (to find nested uses of \step).
}

% \savecounters@TP saves the values of all counters that have ever been defined by \newcounter in the macro
% \restorecounters@TP, which can be used later to restore the saved values. The code is snarfed from amsmath.sty.
% During execution of \stepwise, this is used to restore the values of all counters between steps so that things counted
% in the argument of \stepwise (like equation numbers) do not `run wild'.

\def\@nb@TPfalse{\global\let\if@nb@TP\iffalse}
\def\@nb@TPtrue{\global\let\if@nb@TP\iftrue}
\newtoks\ep@TP
\def\savecounters@TP{%
  \begingroup
    \def\@elt##1{\global\csname c@##1\endcsname\the\csname c@##1\endcsname}%
    \xdef\restorecounters@TP{\cl@@ckpt}%
  \endgroup
  \if@nobreak\@nb@TPtrue\else\@nb@TPfalse\fi
  \global\ep@TP\everypar
  }

% \saveTPcounters@TP saves the values of all `stepwise-specific' counters in the macro \restoreTPcounters@TP.
% This is used to `counteract' \restorecounters@TP, leaving the values of `stepwise-specific' counters intact.
\def\saveTPcounters@TP{%
  \begingroup
    \def\@elt##1{\global\csname c@##1\endcsname\the\csname c@##1\endcsname}%
    \xdef\restoreTPcounters@TP{\cl@@ckpt@TP}%
  \endgroup
  }

% This list gives the names of all `stepwise-specific' counters.
\def\cl@@ckpt@TP{\@elt{totalsteps}\@elt{firststep}\@elt{step}\@elt{stepcommand}\@elt{stepsperformed}\@elt{o@fs@TP}}

% \releasecounter{<name>} inserts <name> into the list \cl@@ckpt@TP. This way, the counter <name> is not restored
% between steps.
\newcommand{\releasecounter}[1]%
{\expandafter\def\expandafter\cl@@ckpt@TP\expandafter{\cl@@ckpt@TP\@elt{#1}}}

% \disable@counting@TP is executed when counting \step commands. Everything the execution of which would be harmful
% during counting, or which needs much computing resources, can be disabled here.
\newcommand{\disable@counting@TP}
{%
  \let\afterstep=\@gobble
  \renewcommand{\backgroundstyle}[2][]{}%
  \renewcommand{\@@vgradrule@TP}[3][0pt]{}%
  \renewcommand{\@@@@dblvgradrule@TP}[3][0pt]{}%
  \renewcommand{\@@hgradrule@TP}[3][0pt]{}%
  \renewcommand{\@@@@dblhgradrule@TP}[3][0pt]{}%
}


% The boolean instepwise@TP indicates whether the execution of \stepwise is currently going on.
\newboolean{instepwise@TP}

%% \@stepwise@TP implements the functionality of \stepwise. It is called by \stepwise after checking for the star.

\newcommand{\@stepwise@TP}[2][]
{%
  \save@TP%                               Save the current contents of the page.
  \savecounters@TP%                       Save the values of all counters.
  \dumpcolorset{stwcolors}%               Make a copy of all color definitions.
  \begingroup%                            A group makes redefinitions local.
    \setboolean{instepwise@TP}{true}%     Set indicatior.
    \let\step\proper@step@TP%             By default, \step executes \proper@step@TP.
    \let\bstep\proper@bstep@TP%
    \let\dstep\proper@dstep@TP%
    \let\vstep\proper@vstep@TP%
    \let\switch\proper@switch@TP%         By default, \switch executes \proper@switch@TP.
    %
    % One big problem with math is that \mathchoice typesets its argument four times. If \step commands are inside the
    % argument of \mathchoice, counters (which are advanced globally by \step) go astray. So far, I don't know any
    % remedy for this apart from (locally) hacking \mathchoice. I know this is a very fragile and non-recommended
    % method, but it works for the examples and will hopefully do until someone helps me find a better solution. 
    \let\orig@mathchoice@TP=\mathchoice%  Save the current definition of \mathchoice...
    \def\mathchoice##1##2##3##4%          ... and redefine.
    {%
      \orig@mathchoice@TP%                The original definition of \mathchoice is called...
      {##1}%                              ... with the first argument untouched and in all other arguments, \step ...
      {\let\step\restep\let\bstep\rebstep\let\dstep\redstep\let\vstep\revstep\let\switch\reswitch##2}% ... redefined ...
      {\let\step\restep\let\bstep\rebstep\let\dstep\redstep\let\vstep\revstep\let\switch\reswitch##3}% ... to execute ...
      {\let\step\restep\let\bstep\rebstep\let\dstep\redstep\let\vstep\revstep\let\switch\reswitch##4}% ... \restep.
      }%
    %
    \c@stepcommand=0\relax%               Initialize the counter for \step commands.
    \let\@@switch@TP=\count@em@TP%        Next, we count the \step commands in <contents>...
    \setbox\tempbox@TP%                    ... by putting <contents> into a \vbox (which is then discarded). 
    =\vbox
    {\disable@counting@TP#2}%             Inside the \vbox, some commands are redefined for safety and efficiency.
    \c@totalsteps=\c@stepcommand%         Now, we know the total number of \step commands.
    %
    % Next, we have to reset \first@TP@<n> for <n>=0...\value{totalsteps}.
    \c@step=0\relax
    \loop
     \ifnum\c@step<\c@totalsteps
      \advance\c@step by 1\relax
      \expandafter\let\csname first@TP@\the\c@step\endcsname=\@undefined% \first@TP@<n>=\@undefined means step <n>
                                                                        % hasn't yet been activated.
    \repeat
    %
    % Next, the optional argument of \stepwise is executed. At this point, \value{totalsteps} already has its final
    % value and \value{step} has not yet been set to \value{firststep}, so both totalsteps and firststep can
    % meaningfully be modified in <settings>.
    #1%
    %
    \c@step=\c@firststep%                   Set the counter for the current step to its starting value...
    \c@stepsperformed=0\relax%              ... and also the counter for the \step commands which are already activated.
    \let\@@switch@TP=\@switch@TP%           \step will now act normally.
    \ifthenelse{\boolean{verbose@TP}}%      Some accounting info (if verbose option is set).
    {\PackageInfo{texpower}{Total number of step commands: \the\c@totalsteps}}
    {}%
    %     
    \ifthenelse{\boolean{display}}%         Are dynamic features enabled?
    {}% Yes.
    {%  No. Do only one loop.
      \c@stepsperformed=\c@totalsteps%      Set everything up for the last loop.
      \c@step=0\relax%                      Set \first@TP@<n> for <n>=0...\value{totalsteps}.
      \loop
       \ifnum\c@step<\c@totalsteps
        \advance\c@step by 1\relax
        \expandafter\let\csname first@TP@\the\c@step\endcsname=\@empty% \first@TP@<n>=\@empty means step <n>
                                                                      % has already been activated.
      \repeat
      \advance\c@step by 1\relax%           This way, the last step won't think it's `first activated'.
      }%
    \let\insertdup@TP=\insertfirstduplicate@TP% Setup command to restore page contents for the first time.
    \loop%                                  This is the central loop.
      \c@stepcommand=0\relax%               Initialize the counter for the current \step command.
      \saveTPcounters@TP%                   Save the `stepwise-specific' counters.
      \restorecounters@TP%                  Restore the `original' values of all counters...
      \restoreTPcounters@TP%                ... and the current values of the `stepwise-specific' counters.
      \let\@afterstep@TP=\relax%            Reset the container for \afterstep.
      %   
      \insertdup@TP%                        Insert saved page contents.
      \begin{stepcapsule}%                  This is usually empty, but may start a minipage (or whatever).
        \usecolorset{stwcolors}%            Restore colors to state at the beginning of \stepwise.
        \if@nb@TP\@nobreaktrue\else\@nobreakfalse\fi
        \global\everypar\ep@TP
        #2%                                 Execute <contents>
      \end{stepcapsule}%
      %                                 
      \@afterstep@TP%                       Whatever has been saved with \afterstep is now executed.
     \ifnum\c@stepsperformed<\c@totalsteps% Doing one more round?
      \outputduplicate@TP%                  Shipout this page and round we go again.
      \let\insertdup@TP=\insertsecondduplicate@TP% Setup command to restore page contents for subsequent times.
      \advance\c@step by 1\relax%           Round we go again
    \repeat
  \endgroup
  \global\c@firststep=\c@o@fs@TP\relax%     Restore default value of counter firststep.
}% End of the definition of \@stepwise@TP


\InputIfFileExists{/etc/texpower/tpsettings.cfg}{}{}%     This file can contain system-specific settings.



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% fill-column: 120
% TeX-master: "dummy"
% End: 

%%
%% End of file `texpower.sty'.