Dialog is shown not centered

import QtQuick 2.2
import QtQuick.Window 2.1
import QtQuick.Dialogs 1.2
import QtQuick.Controls 1.2

Window {
    visible: true
    width: 360
    height: 360

    Button {
        anchors.centerIn: parent
        text: "Push me"
        onClicked: testDialog.visible = true
    }

    MessageDialog {
        id: testDialog
        modality: Qt.ApplicationModal
        title: "MessageDialog"
        text: "This dialog must be centered in parent window"
        standardButtons: StandardButton.Ok
        visible: false
    }
}