anchor.diff:        ++ optional (elem "virtualbox" driverNames) xorg.xrefresh
         ++ optional (elem "ati_unfree" driverNames) kernelPackages.ati_drivers_x11;
   
  +    services.acpid.enable = mkIf needsAcpid true;
  +
       environment.pathsToLink =
         [ "/etc/xdg" "/share/xdg" "/share/applications" "/share/icons" "/share/pixmaps" ];
   
  
positive.code:   };
  
    driverNames = config.hardware.opengl.videoDrivers;
  
    drivers = flip map driverNames
      (name: { inherit name; driverName = name; } //
  
negative.code:     systemd.services."display-manager" =
        { description = "X11 Server";
  
          after = [ "systemd-udev-settle.service" "local-fs.target" ]
                  ++ optional needsAcpid "acpid.service";
  
          restartIfChanged = false;
  
  