Comment 8 for bug 1228336

Can be easily reproduced by holding the phone in landscape mode and tapping with both thumbs quickly on one edge.

The reason it crashes is because DirectionalDragArea starts a new DragGesture for the second finger even though it is a TouchEnd event. on the next run it can't find that finger any more (as the TouchEnd signalizes the finger was removed) and the logic to process the gesture crashes.