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

	C.g_menu_append_submenu(v.native(), cstr1, submenu.native())
}
func (v *Menu) AppendSubmenu(label string, submenu *MenuModel) {
	cstr1 := (*C.gchar)(C.CString(label))
	defer C.free(unsafe.Pointer(cstr1))

	C.g_menu_append_submenu(v.native(), cstr1, submenu.native())
}
// AppendSubmenu is a wrapper around g_menu_append_submenu().