I have made a class from MWindow.
I'm trying to use paintevent/QPainter to paint into it.
However, error is displayed every time paintevent is called:

QPainter::begin: Widget painting can only begin as a result of a paintEvent
QPainter::setPen: Painter not active

Any Ideas? I'm using MWindow since it has openGL enabled and I'm going to need to display multiple sprites. Suggestions?