[OS X] QTouchEvent massive lag on update()

Calling QWidget::update() while QTouchEvent is received causes massive lag in some circumstances, like making the window sufficiently bigger or entering full screen (even after returning from it!).

Attached is an modified imagegestures example, demonstrating the problem, by reimplementing widget's touch events. Note that even after commenting out the drawing code in paint event, lag is still present, though to lesser extent!

P.S. While testing I stumbled upon another problem that the concrete example. When fullscreen is entered (double click) no touch events, and no QPanGesture-s are received!