anchor.diff: -{ composableDerivation, fetchurl, pkgconfig, xlibsWrapper, inputproto, libXi
  -, freeglut, mesa, libjpeg, zlib, libXinerama, libXft, libpng
  +{ composableDerivation, fetchurl
  +, freeglut, mesa, libjpeg, zlib, xorg, libpng
   , cfg ? {}
   , automake, autoconf, libtool
   }:
  
positive.code:       --replace 'class Fl_XFont_On_Demand' 'class FL_EXPORT Fl_XFont_On_Demand'
    '';
  
    propagatedBuildInputs = [ xlibsWrapper inputproto libXi freeglut ];
  
    enableParallelBilding = true;
  
    nativeBuildInputs = [
      pkgconfig
      automake autoconf libtool # only required because of patch
    ];
  
  
negative.code:     // edf { name = "localjpeg"; disable = { buildInputs = [libjpeg]; }; } #       use local JPEG library, default=auto
      // edf { name = "localzlib"; disable = { buildInputs = [zlib]; }; } #       use local ZLIB library, default=auto
      // edf { name = "localpng"; disable = { buildInputs = [libpng]; }; } #       use local PNG library, default=auto
      // edf { name = "xinerama"; enable = { buildInputs = [xorg.libXinerama]; }; } #       turn on Xinerama support default=no
      // edf { name = "xft"; enable = { buildInputs=[xorg.libXft]; }; } #            turn on Xft support default=no
      // edf { name = "xdbe"; };  #           turn on Xdbe support default=no
  
    cfg = {
  