[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 [Expected result]: - Elements move with the page and don't bounce while scrolling. [Actual result]: - Elements bounce when scrolling. [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 the bounce is less obvious.

Regression window: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=738d8ee106fe&tochange=af67b5f73381 Regressed by: Bug 1157745

force enabled APZ, Regression window (good with wheel -> mouse wheel stops working -> bad jumping with wheel): 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

This is effectively a scroll-linked effect, because the page is updating the position of the animation boxes on every animation frame. We scroll async but the updating happens on the main thread and so it can be a little out of sync.

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #3) > This is effectively a scroll-linked effect, because the page is updating the > position of the animation boxes on every animation frame. We scroll async > but the updating happens on the main thread and so it can be a little out of > sync. Do we expect to be able to do anything about this on our side? Or is this a Tech Evangelism bug now?

Disabling such buggy APZ is enough. And this is definitely on our side.

Too late to fix in 53. Looks like this will become graphics team backlog.

(In reply to Botond Ballo [:botond] from comment #4) > Do we expect to be able to do anything about this on our side? Or is this a > Tech Evangelism bug now? Yes, I think it's a TE bug. (In reply to Alice0775 White from comment #5) > Disabling such buggy APZ is enough. And this is definitely on our side. I don't think this is just on our side. I see the same behaviour in Chrome on Windows, for example, if I have a build going in the background eating up my CPU and slowing things down. I can see the text on the page sometimes overlapping the webgl animations if I scroll fast with the mousewheel, as the animations are delayed in repositioning.

I'm not able to reproduce the issue anymore. [Tested with:] Browser / Version: Firefox Nightly 63.0a1 (2018-07-04) Operating System: Windows 10 Pro