1639576 - [Intermittent] Firefox menu flickers when opened after restart or with a new profile

Status: NEW

(Firefox :: Menus, defect, P3)

Description

[Alexandru Trif, QA [:atrif]]

Affected versions

• 78.0a1 (20200520033931)
• 77.0b8 (20200519220135)
• 76.0.1 (20200507114007)

Affected platforms

• macOS 10.12
• macOS 10.15

Steps to reproduce

1. Open Firefox with a new profile and click on the hamburger menu.

Expected result

• No visual glitches are presented.

Actual result

• Firefox menu flickers on opening. If not restart Firefox and try again.

Regression range

• Will search for one ASAP.

Notes

• Attached a screen recording.
• The issue may be intermittent.

Comment 1

[Alexandru Trif, QA [:atrif]]

Attachment: hamburger menu.mov

Comment 2

[(Away until May 24) Jared Wein [:jaws] (please needinfo? me)]

Attachment: Screenshot of flicker

When the menu first appears it is missing the arrow at the top. Dao, could this be related to a recent panel bindings change?

Comment 3

[Dão Gottwald [::dao]]

This sounds similar to bug 1633356. The offending patches were backed out there, so I don't know what may have caused this.

Alexandru, have you found the regression range yet?

Comment 4

[Alexandru Trif, QA [:atrif]]

I tried searching for a regression range but this is highly intermittent. I saw this happening on a Nightly build from 2019-12-02 but I don't think it is possible to find a regression until some solid STR are found due to the fact that this is happening only when the menu is opened for the first time and lots of restarts are required. I think that this is different from bug 1633356 due to the fact that this is very intermittent and the older builds are affected too.

Comment 5

[:Gijs (he/him)]

AFAICT there's no guarantee that the arrow image for the panel has loaded before it's being shown. See also e.g. bug 1641478 which is about a similar problem but for stylesheets (which, with bug 1633356 fixed by backing out the patches that moved the stylesheets into the binding, doesn't apply to the hamburger panel anymore).

bug 1648939 also improved things a bit here for macOS, but I suspect if this is still broken, we would want to either:

1. preload the image, or
2. give the <image> fixed dimensions (e.g. via the CSS at https://searchfox.org/mozilla-central/rev/85ae3b911d5fcabd38ef315725df32e25edef83b/toolkit/themes/osx/global/popup.css#75-95), or
3. somehow delay showing the panel until the image has loaded.

That is... assuming this still happens? :atrif, can you confirm? It's a little surprising this got filed as a mac bug, as I'd expect delays in loading the panel arrow to affect other OSes, too.

Comment 6

[Alexandru Trif, QA [:atrif]]

I tried several times on macOS 10.12 and Windows 10x64 with Nightly (20200714083249) performing multiple restarts and new profiles and I cannot see the issue occurring anymore. I think I saw it once happening in Firefox 79.0b7 after many attempts on macOS 10.12 due to its intermittency.
On Ubuntu 18 I encountered bug 1652743 on Nightly and I saw a similar flickering when bisecting the bug. On Ubuntu 18.04, I can still see a similar flickering on 79.0b7 but it's intermittent.