glib/menu.go
func MenuItemNewSubmenu(label string, submenu *MenuModel) *MenuItem {
	cstr1 := (*C.gchar)(C.CString(label))
	defer C.free(unsafe.Pointer(cstr1))

	c := C.g_menu_item_new_submenu(cstr1, submenu.native())
	if c == nil {
		return nil
	}
	return wrapMenuItem(wrapObject(unsafe.Pointer(c)))
}
func MenuItemNewSubmenu(label string, submenu *MenuModel) *MenuItem {
	cstr1 := (*C.gchar)(C.CString(label))
	defer C.free(unsafe.Pointer(cstr1))

	c := C.g_menu_item_new_submenu(cstr1, submenu.native())
	if c == nil {
		return nil
	}
	return wrapMenuItem(wrapObject(unsafe.Pointer(c)))
}
// MenuItemNewSubmenu is a wrapper around g_menu_item_new_submenu().