Yes, my changes are risky.

My App users are children, and they often use their fingers to control the blocks on the pad. I have received many feedback saying that the blocks sometimes move unexpectedly. I watched their screen records attached, and I'm sure the problem is caused by the unhandled pointercancel event.

In order to quickly fix this problem, I temporarily patched my code in my App. I listen to the pointercancel event and emit a pointerup event to the workspace when I receive a pointercancel event. After doing this about a week ago, I haven't received any report on this problem till now.

Since I haven't fully read the code of Blockly, I think my PR may be inconsiderate. If so, I'm looking forward to your advice on how to fix the problem more sensibly.