{ config, lib, pkgs, ... }: with lib; let cfg = config.services.xserver.windowManager.metacity; inherit (pkgs) gnome3; in { options = { services.xserver.windowManager.metacity.enable = mkEnableOption "metacity"; }; config = mkIf cfg.enable { services.xserver.windowManager.session = singleton { name = "metacity"; start = '' ${gnome3.metacity}/bin/metacity & waitPID=$! ''; }; environment.systemPackages = [ gnome3.metacity ]; }; }