anchor.diff:          # "utilities-terminal" and "accessories-text-editor".
           pkgs.gnome.gnomeicontheme
           pkgs.desktop_file_utils
  -      ]
  -      ++ optionals isXfce48 [
           pkgs.xfce.libxfce4ui
           pkgs.xfce.garcon
           pkgs.xfce.thunar_volman
  
positive.code:     environment.pathsToLink =
        [ "/share/xfce4" "/share/themes" "/share/mime" "/share/desktop-directories" ];
  
      environment.shellInit = optionalString isXfce48
        ''
          export GIO_EXTRA_MODULES=${pkgs.xfce.gvfs}/lib/gio/modules
        '';
  
      # Enable helpful DBus services.
      services.hal = mkIf (!isXfce48) { enable = true; };
      services.udisks = mkIf isXfce48 { enable = true; };
      services.upower = mkIf (isXfce48 && config.powerManagement.enable) { enable = true; };
  
    };
  
  
negative.code:       };
  
      environment.systemPackages =
        [ pkgs.gtk # To get GTK+'s themes.
          pkgs.hicolor_icon_theme
          pkgs.shared_mime_info
          pkgs.which # Needed by the xfce's xinitrc script.
  