anchor.diff:  
       environment.kdePackages = mkOption {
         default = [];
  -      example = [ pkgs.kde4.kdesdk ];
  +      example = "[ pkgs.kde4.kdesdk ]";
         type = types.list types.package;
         description = "This option is obsolete.  Please use <option>environment.systemPackages</option> instead.";
       };
  
positive.code:           pkgs.shared_mime_info
            xorg.xmessage # so that startkde can show error messages
            xorg.xset # used by startkde, non-essential
          ]
        ) ++ config.environment.kdePackages;
  
  
negative.code:             # installing new applications to update the cache.
              # See http://lists-archives.org/kde-devel/26175-what-when-will-icon-cache-refresh.html
              rm -fv $HOME/.kde/cache-*/icon-cache.kcache
  
              # Qt writes a weird ‘libraryPath’ line to
              # ~/.config/Trolltech.conf that causes the KDE plugin
              # paths of previous KDE invocations to be searched.
              # Obviously using mismatching KDE libraries is potentially
              # disastrous, so here we nuke references to the Nix store
              # in Trolltech.conf.  A better solution would be to stop
              # Qt from doing this wackiness in the first place.
              if [ -e $HOME/.config/Trolltech.conf ]; then
                  sed -e '/nix\\store\|nix\/store/ d' -i $HOME/.config/Trolltech.conf
              fi
  
              # Start KDE.
              exec ${pkgs.kde4.kdebase_workspace}/bin/startkde
  