code: func RadioMenuItemNewWithLabelFromWidget(group *RadioMenuItem, label string) (*RadioMenuItem, error) {
  	cstr := C.CString(label)
  	defer C.free(unsafe.Pointer(cstr))
  	c := C.gtk_radio_menu_item_new_with_label_from_widget(group.native(),
  		(*C.gchar)(cstr))
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	return wrapRadioMenuItem(glib.Take(unsafe.Pointer(c))), nil
  }
docs: // RadioMenuItemNewWithLabelFromWidget is a wrapper around
  // gtk_radio_menu_item_new_with_label_from_widget().