In our application QDragManager::drag crashes at the line [dndParams.theEvent locationInWindow].

The reason is that dndParams.theEvent is not pointing to a valid NSEvent. We are not calling QDrag::exec inside the actual MouseMove event but once we have processed some further events and it seems the NSEvent for the mouse event has become invalid by then.

Would it be possible to remove the dependency on the event object from the mouse drag event? This dependency does not seems to be required for Windows or Linux.
It could also be worth investigating if a RetainEvent will keep the pointer to theEvent alive.