anchor.diff:      "TestScorer"
       "VIMGUI"
       "VecStatGraphs3D"
  -    #"VisuClust"
       "WMCapacity"
       "accrual"
       "ade4TkGUI"
  
positive.code:     qtpaint = old.qtpaint.override { hydraPlatforms = stdenv.lib.platforms.none; };
      bamboo = old.bamboo.override { hydraPlatforms = stdenv.lib.platforms.none; };
  
      # Obsolete package that I keep around temporarily because some
      # existing code depends on it.
      Defaults = derive {
        name="Defaults";
        version="1.1-1";
        sha256="0ikgd5mswlky327pzp09cz93bn3mq7qnybq1r64y19c2brbax00d";
      };
    };
  in
    self
  
negative.code:     gmatrix = [ pkgs.cudatoolkit ];
      WideLM = [ pkgs.cudatoolkit ];
      RCurl = [ pkgs.curl ];
      R2SWF = [ pkgs.pkgconfig ];
      RGtk2 = [ pkgs.pkgconfig ];
      RProtoBuf = [ pkgs.pkgconfig ];
  