anchor.diff:    desktopItem = makeDesktopItem {
       name = browserName;
       exec = browserName + " %U";
  -    icon = icon;
  +    icon = "$out/icons/firefox.png";
       comment = "";
       desktopName = desktopName;
       genericName = "Web Browser";
  
positive.code:       "text/html"
        "text/xml"
        "application/xhtml+xml"
        "x-scheme-handler/http"
        "x-scheme-handler/https"
        "x-scheme-handler/ftp"
        "x-scheme-handler/mailto"
        "x-scheme-handler/webcal"
        "x-scheme-handler/about"
        "x-scheme-handler/unknown"
      ];
    };
  
  
negative.code:     ''
      }
  
      mkdir -p $out/share/icons
      ln -s "$out/lib/firefox-35.0.1/browser/icons/mozicon128.png" "$out/share/icons/firefox.png"
  
      mkdir -p $out/share/applications
      cp $desktopItem/share/applications/* $out/share/applications
  
  