Painting on top of real-time rendering windows

I am developing a QT application that can render a real-time update map. I used a SDK as a slave process and pass it the winId() of the MainWindow and it renders the map in it.

Now I am trying to place some widgets like button or label on top of this window to control the map view port. However, placing a button widget on top of the map widget does not serve the purpose as it gets painted over and over by the map widget. The button often was covered by the map because of the map widget's repaint action.


I found similar case by google. This guy's problem is about placing widget on top of a real time render video. But I think it should be same problem.
(http://stackoverflow.com/questions/1...in-a-qt-widget).

Any workaround way? or suggestion about it?

Could any one give me some advice about this problem. Thanks a lot.