QLabel/QWidget with transparency is not rendered on top of Phonon::VideoWidget

In the attached testapp, I attempt to render a semi transparent QLabel over a VideoWidget during playback. Please specify the name of a valid video in the source code in order to try the app.

Expected result: Label with current video playback position timestamp is rendered over the video playback - If you compile the same app on Windows, you will see this behavior.
Actual result: Only video playback is seen, the label is not.

Another example with similar problem is also attached here. please copy Wildlife.wmv file from your windows video folder to see the problem.