Qt Code:
  1. QRectF target(100.0, 100.0, 100.0, 100.0);
  2. QRectF source(100.0, 100.0, 100.0, 100.0);
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Is the problem, by any chance, that you don't see any pixmap?
Try drawing everything relative to (0,0), not (100, 100).
Also, overwrite QAbstractButton::sizeHint() and return your size hint( which probably is the size of one of the pixmaps ).

Regards