Markus Stange [:mstange] Reporter
	Description • 8 years ago

http://panamapapers.sueddeutsche.de/en/ behaves differently with APZ than without APZ if you scroll it slowly on a Mac touchpad. This page has a DOMMouseScroll handler but no wheel handler. It calls preventDefault() on every DOMMouseScroll event.

Main thread scrolling has a mechanism to ignore pixel scrolls that come after a preventDefault()ed DOMMouseScroll event. We need to check why this mechanism doesn't apply to APZ scrolling.

	Markus Stange [:mstange] Reporter
	Comment 1 • 8 years ago

Hmm, testing this again, I'm not sure that that's what's happening. Even with APZ off we sometimes seem to pixel scroll the page.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com)
	Comment 3 • 8 years ago

I was seeing this weird scroll behaviour on Aurora 49, then I tried testing in 48 and 50 but didn't see it there. And now I can't see in 49 either. I don't know what's going on with this page, it seems to change behaviour a lot. Punting from 48.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com)
	Comment 4 • 8 years ago

I still see this in Nightly and Aurora, although not all the time. Loading the page in a private window seems to repro it reliably.