import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {
    id: window
    width: 300
    height: 300
    visible: true

    Component.onCompleted: mb.addMenu(cmp.createObject(mb))

    menuBar: MenuBar {
        id: mb
        width: parent.width
        Menu {
            title: "This Works"

            MenuItem { text: "Cut" }
            MenuItem { text: "Copy" }
            MenuItem { text: "Paste" }
        }
    }

    Component {
        id: cmp
        Menu {
            title: "This Doesn't"

            MenuItem { text: "Cut" }
            MenuItem { text: "Copy" }
            MenuItem { text: "Paste" }
        }
    }
}