anchor.diff:        default = false;
         example = true;
         description = "Enable Gnome 3 desktop manager.";
  +    };
  +
  +    services.xserver.desktopManager.gnome3.sessionPath = mkOption {
  +      default = [];
  +      example = "[ pkgs.gnome3.gpaste ]";
  +      description = "Additional list of packages to be added to the session search path.
  +                     Useful for gnome shell extensions or gsettings-conditionated autostart.";
  +      apply = list: list ++ [ gnome3.gnome_shell ]; 
       };
   
       environment.gnome3.packageSet = mkOption {
  
positive.code: 
            export XDG_MENU_PREFIX=gnome
  
            # Don't let epiphany depend upon gnome-shell
            # Don't let gnome-session depend upon vino (for .desktop autostart condition)
            # Override default mimeapps
            export XDG_DATA_DIRS=$XDG_DATA_DIRS''${XDG_DATA_DIRS:+:}${gnome3.gnome_shell}/share/gsettings-schemas/${gnome3.gnome_shell.name}:${gnome3.vino}/share/gsettings-schemas/${gnome3.vino.name}:${mimeAppsList}/share
  
            # Let gnome-control-center find gnome-shell search providers
            export GNOME_SEARCH_PROVIDERS_DIR=${config.system.path}/share/gnome-shell/search-providers/
  
negative.code:         gnome3.gnome_settings_daemon
          gnome3.gnome_shell
          gnome3.gnome_themes_standard
        ] ++ cfg.sessionPath ++ (removePackagesByName [
          gnome3.baobab
          gnome3.empathy
          gnome3.eog
  