anchor.diff:          environments you probably want to add them yourself.
         '';
       };
  +
  +    gtkUsePortal = mkOption {
  +      type = types.bool;
  +      default = false;
  +      description = ''
  +        Sets environment variable <literal>GTK_USE_PORTAL</literal> to <literal>1</literal>.
  +        This is needed for packages ran outside Flatpak to respect and use XDG Desktop Portals.
  +        For example, you'd need to set this for non-flatpak Firefox to use native filechoosers.
  +        Defaults to <literal>false</literal> to respect its opt-in nature.
  +      '';
  +    };
     };
   
     config =
  
positive.code: { config, pkgs ,lib ,... }:
  with lib;
  {
    options.xdg.portal = {
      enable =
  
negative.code: 
      in mkIf cfg.enable {
  
        assertions = [
          { assertion = (cfg.gtkUsePortal -> cfg.extraPortals != []);
            message = "Setting xdg.portal.gtkUsePortal to true requires a portal implementation in xdg.portal.extraPortals such as xdg-desktop-portal-gtk or xdg-desktop-portal-kde.";
          }
        ];
  
        services.dbus.packages  = packages;
        systemd.packages = packages;
  
        environment.variables = {
          GTK_USE_PORTAL = optional cfg.gtkUsePortal "1";
          XDG_DESKTOP_PORTAL_PATH = map (p: "${p}/share/xdg-desktop-portal/portals") cfg.extraPortals;
        };
      };
  