Windows: MessageDialog causes warnings on close on application exit

import QtQuick 2.1
import QtQuick.Window 2.1
import QtQuick.Dialogs 1.1
import QtQuick.Controls 1.1

Window {
    Button {
        text: "Open"
        anchors.centerIn: parent
        onClicked: dialog.open()
    }
    MessageDialog {
        id: dialog
        text: "QtQuick.Dialogs.MessageDialog"
    }
}

External WM_DESTROY received for  QWidgetWindow(0x4191778, name = "QMessageBoxClassWindow") , parent:  QObject(0x0)  , transient parent:  QQuickWindowQmlImpl(0x107d570)