glib/menu.go
func (v *Menu) InsertSubmenu(position int, label string, submenu *MenuModel) {
	cstr1 := (*C.gchar)(C.CString(label))
	defer C.free(unsafe.Pointer(cstr1))

	C.g_menu_insert_submenu(v.native(), C.gint(position), cstr1, submenu.native())
}
func (v *Menu) InsertSubmenu(position int, label string, submenu *MenuModel) {
	cstr1 := (*C.gchar)(C.CString(label))
	defer C.free(unsafe.Pointer(cstr1))

	C.g_menu_insert_submenu(v.native(), C.gint(position), cstr1, submenu.native())
}
// InsertSubmenu is a wrapper around g_menu_insert_submenu().