anchor.diff:  
     ###### interface
   
  -  options.virtualisation.virtualbox.guest.enable = mkOption {
  -    default = false;
  -    description = "Whether to enable the VirtualBox service and other guest additions.";
  +  options.virtualisation.virtualbox.guest = {
  +    enable = mkOption {
  +      default = false;
  +      type = types.bool;
  +      description = "Whether to enable the VirtualBox service and other guest additions.";
  +    };
  +
  +    x11 = mkOption {
  +      default = true;
  +      type = types.bool;
  +      description = "Whether to enable x11 graphics";
  +    };
     };
   
     ###### implementation
   
  -  config = mkIf cfg.enable {
  -    assertions = [ {
  +  config = mkIf cfg.enable (mkMerge [{
  +    assertions = [{
         assertion = pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64;
         message = "Virtualbox not currently supported on ${pkgs.stdenv.system}";
  -    } ];
  +    }];
   
       environment.systemPackages = [ kernel.virtualboxGuestAdditions ];
   
  
positive.code:         serviceConfig.ExecStart = "@${kernel.virtualboxGuestAdditions}/bin/VBoxService VBoxService --foreground";
        };
  
      services.xserver.videoDrivers = mkOverride 50 [ "virtualbox" "modesetting" ];
  
      services.xserver.config =
  
negative.code:         PATH=${makeBinPath [ pkgs.gnugrep pkgs.which pkgs.xorg.xorgserver.out ]}:$PATH \
            ${kernel.virtualboxGuestAdditions}/bin/VBoxClient-all
        '';
    })]);
  
  }
  