Qml Menu, inherited property "opened" is not working

import QtQuick
import QtQuick.Controls
import QtQuick.Window

Window{
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Button{
        id:button
        anchors.centerIn: parent
        text: "menu button"
        onClicked: {
            print(menu.opened)
            if(menu.opened){
                menu.close()
            }
            else{
                menu.open()
            }
        }
    }
    Menu {
        id: menu

        x: 0
        y: parent.height/2 + button.height/2 + 10

        MenuItem {
            text: "Choix 1"
        }

        MenuItem {
            text: "Choix 2"
        }
    }
}