I've encountered a hang inside QCocoaEventDispatcher::processEvents.
What happens (quite difficult to explain to be honest):
Check the attached screenshot. We are 2 times in QCocoaEventDispatcher::processEvents(). So my previous dialog just closed, endModalSession called, d->interrupt became true, no cleanup session yet. Then I go to 'second' processEvents which is called from QApplication::processEvents, no real dialog here (without exiting the loop in 'first' processEvents) and d->interrupt becomes false again. As a result the loop in 'first' processEvents becomes endless.

It all looks exactly like QTBUG-45389 which is closed by some reason. I've attached the patch which helps me. Basically I just added cleanupModalSessions into the hanging loop. Could somebody review it and apply if possible?