[Affected versions]: - Windows 7 64bit - Windows 10 32bit - Ubuntu 16.04 64bit - Mac OS X 10.11.5 [Affected platforms]: - Firefox 53.0.2 - Firefox 54.0b7 - latest Nightly 55.0a1 [Steps to reproduce]: 1. Open https://threejs.org/examples/#webgl_multiple_elements_text 2. Scroll inside demo, but over the elements [Expected result]: - Scrolling in the page stops when cursor hits one graphic element and it continues to zoom inside the element. [Actual result]: - Even though mouse cursor reaches a graphic element the scroll continues until it reaches the bottom of the page. [Regression range]: - This is not a recent regression, I was able to reproduce on Fx 50.0.2 as well - I did not reproduce on Nightly from 2014-01-08 (I will provide a regression range ASAP) so this is an old regression. [Additional notes]: - For some reason on macOS 10.12.4 on my iMac this issue does not exist.

[Tracking Requested - why for this release] user interaction is broken. Regression window: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=738d8ee106fe&tochange=af67b5f73381 Regressed by: Bug 1157745 force enabled APZ, Regression window (good -> scroll w/ mouse wheel stops working -> bad): https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=c3376e427908&tochange=1b0655f6b110 https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=4f4454ece5ac&tochange=098390cdba51 Regressed by: bug 1147223, Bug 1168630

Tracking 55+ for this APZ regression issue.

Scrolling inside the elements should not scroll the page at all - the elements have wheel listeners which do preventDefault calls. This looks like we're probably not setting up the event regions properly, and so APZ is scrolling without waiting for the main thread. Either that or we're hitting the timeout because of main thread slowness. Seems like a bug on our side at any rate.

Too late to fix in 53, I'm going to say it seem unlikely for 54 as well and is not urgent, or a recent regression.

This is tagged as a P3. Untracked for 55 as I doubt if this will get fixed by Aug 8th, tracked for 56+. If it gets fixed in time and is low-risk, we can consider uplifting to Beta55.

I don't think we need to track this for 56 either, looks like it's been triaged and is in the APZ team backlog.

Mass bug change to replace various 'parity' whiteboard flags with the new canonical keywords. (See bug 1443764 comment 13.)