nixos/graphical-desktop: add enable option

  ...

}:

let

  cfg = config.services.graphical-desktop;

  xcfg = config.services.xserver;

  dmcfg = config.services.displayManager;

in

{

  config = lib.mkIf (xcfg.enable || dmcfg.enable) {

  options = {

    services.graphical-desktop.enable =

      lib.mkEnableOption "bits and pieces required for a graphical desktop session"

      // {

        default = xcfg.enable || dmcfg.enable;

        defaultText = lib.literalExpression "(config.services.xserver.enable || config.services.displayManager.enable)";

        internal = true;

      };

  };

  config = lib.mkIf cfg.enable {

    # The default max inotify watches is 8192.

    # Nowadays most apps require a good number of inotify watches,

    # the value below is used by default on several other distros.