ios: no more touch events after we close and reopen the application

when I try the "quick1cinematic" example on my iPad, from time to time the application freezes when I close and reopen it.

I think this is not the only way to trigger the bug, but at least this sequence seems to make it freeze all the time:

• touch the screen with two fingers.
• while the two fingers are still touching the screen, press the iPad button to exit the application.
• reopen it: there is no way to interact anymore, and the application has to be killed.

As a quick hack, I found out that commenting the line:

if (self->lastTouchType == QEvent::TouchCancel && e->touchType != QEvent::TouchBegin) return

in "qguiapplication.cpp" solves the bug.