Repaint child without repainting parent widget

[Tsweti]

I have a parent widget ( QScrollArea ) to which I setWidget my custom QFrame containing some buttons. The QScrollArea has background set with stylesheet and my widget has transparent background. I want to make the QScrollArea not redraw its background each time my widget is moved because this slows down performance very much.

What can I do?

[Tsweti]

The Qt::WA_OpaquePaintEvent seems to be what I need but setting this to the scroll area still erase the background before the paintEvent is called.