1498962 - Bugzy's gray bar animation has a white horizontal line when WebRender is enabled

Status: VERIFIED DUPLICATE of bug 1501195

(Core :: Graphics: WebRender, defect, P3)

Description

[Chris Peterson [:cpeterson]]

Attachment: WebRender_screenshot.png

STR:
1. Enable WebRender
2. Load http://as-bugzy.herokuapp.com/my_bugs
3. Enter your Bugzilla email address

RESULT:
The page's loading animations (the gray vertical bars) have a white horizontal line where the gray vertical bars align. See the attached screenshot.

I am running macOS 10.14 Mojave on a MacBook Pro with a Retina display.

I think this bug is a regression in Firefox 60 Nightly from stacking context bug 1426386. I bisected this bug to the following pushlog:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=de52bf2201a6992df26d0e7c7c1223266bcda4f9&tochange=3dea9196184747f4987cbc95d7d11b8e934a3d11

Comment 1

[Jeff Muizelaar [:jrmuizel]]

This seems fixed. Please reopen if not?

Comment 2

[Chris Peterson [:cpeterson]]

Attachment: screenshot-65.0a1.jpg

I can still reproduce this bug in 65 Nightly. With WebRender enabled, I see the white lines. With WebRender disabled, I don't see any white lines.

Maybe this is an issue with display scaling? Windows recommends 250% scaling on my laptop (a Razer Blade), but I use 200%. I just tried 250% but I could still see the white lines.

Comment 3

[Sotaro Ikeda [:sotaro]]

I also reproduced the problem on my P50(Win10) with 120%.

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Ok, it sounds very snapping related.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Sounds like next step here would be to create a reduced test case.

Comment 6

[Jamie Nicol [:jnicol]]

Attachment: Reduced test case

Here's a reduced testcase. Reproduces for me at 120%.

Commenting out the transform:translateZ(0) makes it go away.

Comment 7

[Jeff Muizelaar [:jrmuizel]]

This may be the same cause as bug 1501195

Comment 8

[Andrew Osmond [:aosmond] (he/him)]

Build 20190124104034 and later contains the fix (Windows not out yet but confirmed it is fixed on Linux).

Comment 9

[Chris Peterson [:cpeterson]]

I have confirmed that this bug is also fixed on Windows.