Modal Overlay don't block multi touch

import QtQuick 2.7
import QtQuick.Controls 2.0
import QtQuick.Layouts 1.3

ApplicationWindow {
    visible: true
    width: 640
    height: 480

    ColumnLayout {
        spacing: 10

        ComboBox {
            implicitWidth: 300
            model: ListModel {
                id: model
                ListElement { text: "Banana" }
                ListElement { text: "Apple" }
                ListElement { text: "Coconut" }
            }
        }
        Button {
            property int clickCounter: 0

            implicitWidth: 300
            text: clickCounter
            onClicked: clickCounter++
        }
    }

    Popup {
        id: popup

        x: parent.width - width
        y: parent.height - height
        modal: true
        width: 50
        height: 50
        closePolicy: Popup.NoAutoClose
    }
    Component.onCompleted: popup.open()
}