If a QGraphicsObject which is a recipient of gesture events gets deleted during a gesture sequence (it has accepted GestureStarted but gets deleted before GestureFinished or GestureCanceled) there will be a crash ("The inferior stopped because it received a signal from the Operating System. Signal name: SIGSEGV, Signal meaning: Segmentation fault") in qgraphicsitem.cpp:

/*!
  \since 4.6

  Return the graphics item cast to a QGraphicsObject, if the class is actually a
  graphics object, 0 otherwise.
*/
QGraphicsObject *QGraphicsItem::toGraphicsObject()
{
    return d_ptr->isObject ? static_cast<QGraphicsObject *>(this) : 0;   // <-- crashes because d_ptr is a null pointer
}

Apparently the gesture event dispatching system doesn't take into account that the target may not exist anymore.

NOTE ON THE AUTOTEST:

I was unable to reproduce the exact same crash with the autotest using QTest::touchEvent. The test will nonetheless crash albeit the crash is not the one described above. I was able to reproduce the exact same crash with the autotest when running it on Qt Creator if I inserted a breakpoint somewhere in the gesture event handling function (try line 96 for example). Therefore I have also included a manual test where you can reproduce the crash described above. To do this, press and move within the inner rectangle of the test program.