1718276 - Flickering pixel with SWGL on Github "Start a review" button

Status: RESOLVED DUPLICATE of bug 1791495

(Core :: Graphics: WebRender, defect)

Description

[Markus Stange [:mstange]]

Attachment: swgl-flicker.mov

See the attached screen recording.

Comment 1

[Markus Stange [:mstange]]

This also happens for the regular issue comment form.

Steps to reproduce:

1. Log in with your github account.
2. Go to an open issue in a repo that you have edit rights on, so that the "Close issue" button is displayed under the comment textbox.
3. Type something in the issue comment box.
4. Move your mouse back and forth between the "Close with comment" and "Comment" buttons.

At some point, the white line will appear in the "Comment" button.

Comment 2

[Markus Stange [:mstange]]

(In reply to Markus Stange [:mstange] from comment #1)

4. Move your mouse back and forth between the "Close with comment" and "Comment" buttons.

This takes some time. It looks like the bug starts happening once WR's partial tile invalidation "quad tree" is fine enough that the invalid rect cuts through the button.

Comment 3

[Markus Stange [:mstange]]

Attachment: screen recording with gfx.webrender.debug.picture-caching=true

Comment 4

[Markus Stange [:mstange]]

I cannot reproduce this on my Intel Mac. Only on my M1 Mac.

Comment 5

[Lee Salzman [:lsalzman]]

Superficially this seems something like a strange rounding issue, though I don't have a good guess off-hand what is going on yet.

Does the gfx.webrender.compositor pref influence the result at all?

Comment 6

[Markus Stange [:mstange]]

The bug still happens with gfx.webrender.compositor set to false.
Also, unrelated to this bug, there is pretty intense flickering across the whole window in that configuration.

Comment 7

[Lee Salzman [:lsalzman]]

Markus, can you check if bug 1791495 resolved this?

Comment 8

[Markus Stange [:mstange]]

Yes it did! Thanks!