anchor.diff:      inherit (gtkLibs) gtk;
       inherit (gst_all) gstreamer gstPluginsBase;
       inherit (gnome) GConf;
  +    withMesa = stdenv.isLinux;
     };
   
     wxGTK290 = callPackage ../development/libraries/wxGTK-2.9/2.9.0.nix {
  
positive.code: 
    gnuplot = callPackage ../tools/graphics/gnuplot {
      inherit (gtkLibs) pango;
      wxGTK = if stdenv.isLinux then wxGTK else wxGTK.override { withMesa = false; };
      texLive = null;
      lua = null;
    };
  
negative.code: 
    maxima = callPackage ../applications/science/math/maxima { };
  
    wxmaxima = callPackage ../applications/science/math/wxmaxima { };
  
    pari = callPackage ../applications/science/math/pari {};
  
  