Hello Marco,
What happens to a touch handler when I drag the finger outside the physical touch screen area of the target?
for the touch display it is as if the user had released the finger. In fact, the finger does not touch the screen anymore, so the touch interaction ends and corresponding OnLeave, OnRelease or OnEnd signals are sent.
With the prototyper I am not able to simulate that situation.
That is correct. The interaction with the mouse is very sensitive so it is easy to drag the mouse outside the Prototyper window. Terminating the touch interaction in such case would annoy the user. Actually the unique way to simulate this application case is to release the mouse button explicitly.
I hope it helps you further.
Best Regards
Paul Banach