Cannot show QWidget on top of QQuickView (regression)

My application should show a QWidget on top of a QQuickView. Therefor I use QWidget::createWindowContainer() to show the QQuickView and overlay a QWidget.

In Qt 5.1.1 this worked fine. Now in Qt 5.2 the QWidget is not visible. I've attached an example + an screenshot of the expected result.

Side note: Originally I'm not using QPushButton but QAxWidget. The result there is that the QAxWidget is shown but the QQuickView is no longer visible. Proably the underlaying issue is the same so I decided to go with the simpler example.