Steps to reproduce: 1. Fling a scrollable iframe so that it reaches the end What happens: Once the iframe is scrolled fully, any remaining scrolls generated by the fling will be propagated to its parent frame/page. What should happen instead: The fling should stop once the iframe has scrolled fully.
Created attachment 195396 [details] WIP, not for review
(In reply to comment #1) > Created an attachment (id=195396) [details] > WIP, not for review This patch makes a lot of sense. Summarizing a chat I had with David, it forces handleGestureScrollUpdate() to always return true when the event type is GestureScrollUpdateWithoutPropagation, which indicates that the event was handled even if no scrolling happened. As a result, the parent frame's call to passGestureEventToWidgetIfPossible() at line 2715 evaluates to true and the parent's scrolling code is bypassed. This is exactly what we would like to have happen when propagation is prohibited.
Created attachment 196353 [details] WIP, not for review