code: func MessageDialogNew(parent IWindow, flags DialogFlags, mType MessageType, buttons ButtonsType, format string, a ...interface{}) *MessageDialog {
  	s := fmt.Sprintf(format, a...)
  	cstr := C.CString(s)
  	defer C.free(unsafe.Pointer(cstr))
  	var w *C.GtkWindow = nil
  	if parent != nil {
  		w = parent.toWindow()
  	}
  	c := C._gtk_message_dialog_new(w,
  		C.GtkDialogFlags(flags), C.GtkMessageType(mType),
  		C.GtkButtonsType(buttons), cstr)
  	return wrapMessageDialog(glib.Take(unsafe.Pointer(c)))
  }
docs: // MessageDialogNew() is a wrapper around gtk_message_dialog_new().
  // The text is created and formatted by the format specifier and any
  // additional arguments.