anchor.diff:        export XDG_CONFIG_DIRS=${pkgs.kdebase}/etc/xdg:${pkgs.kdelibs}/etc/xdg
         export XDG_DATA_DIRS=${pkgs.kdebase}/share
         exec ${pkgs.kdebase}/bin/startkde
  +
  +    '' else if sessionType == "kde4" then ''
  +
  +      # Start KDE.
  +      export KDEDIRS=$HOME/.nix-profile:/nix/var/nix/profiles/default:${pkgs.kde42.kdelibs}:${pkgs.kde42.kdebase}:${pkgs.kde42.kdebase_runtime}:${pkgs.kde42.kdebase_workspace}
  +      export XDG_CONFIG_DIRS=${pkgs.kde42.kdelibs}/etc/xdg:${pkgs.kde42.kdebase_runtime}/etc/xdg:${pkgs.kde42.kdebase_workspace}/etc/xdg
  +      export XDG_DATA_DIRS=${pkgs.kde42.kdelibs}/share:${pkgs.kde42.kdebase}/share:${pkgs.kde42.kdebase_runtime}/share:${pkgs.kde42.kdebase_workspace}/share:${pkgs.shared_mime_info}/share
  +      exec ${pkgs.kde42.kdebase_workspace}/bin/startkde
   
       '' else ''
   
  
positive.code:     pkgs.kdebase
      xorg.xset # used by startkde, non-essential
    ]
    ++ optional (videoDriver == "nvidia") [
      kernelPackages.nvidiaDrivers
    ];
  
  
    extraEtc =
      optional (sessionType == "kde")
        { source = "${pkgs.xkeyboard_config}/etc/X11/xkb";
          target = "X11/xkb";
        }
  
negative.code: 
      ### Show a background image.
      # (but not if we're starting a full desktop environment that does it for us)
      ${if sessionType != "kde" && sessionType != "kde4" then ''
      
        if test -e $HOME/.background-image; then
          ${pkgs.feh}/bin/feh --bg-scale $HOME/.background-image
  