playbin - blank areas on screen and various questions

[Harry McKame]

Philippe, I have looked at your code and it's much too heavy for me.
I have copied the following lines but that's not enough - the blank spaces are still there:

     setAutoFillBackground(true);
     setAttribute(Qt::WA_OpaquePaintEvent, false);
     setAttribute(Qt::WA_PaintOnScreen, false);

If GStreamer does not use all the overlay's window, why does it never paint the rest ?
Is my only solution left is to resize the display window to be exactly covered by the video?