1793508 - RFP letterboxing causes overflow in main browser area below ~800px width

Status: VERIFIED FIXED

(Firefox :: Theme, defect)

Description

[Kevin Locke]

Attachment: Screenshot of Firefox Nightly build 20221002212226 showing window with cut off along right edge

Using Firefox Nightly build 20221002212226 with privacy.resistFingerprinting.letterboxing:true, if the browser window has a width less than ~800px, the toolbars and content window can get cut off along the right edge (e.g. the main menu hamburger button can get cut off). The issue appears to occur under a variety of condition. It does appear to be affected by the content of the displayed page. One reliable reproduction I've used:

1. Open a new browser window and resize it to 800px wide.
2. Navigate to https://git-scm.com/docs/git-config
3. Find in page (Ctrl+F) "safe."

When the "." of "safe." is entered in the search box, letterboxing appears along the left side of the browser window and overflow occurs along the right, cutting off the main menu button and the right edge of the page content.

I'm able to reproduce the issue on Sway and Mutter using either a native Wayland window or XWayland window. Bisection with mozregression --pref privacy.resistFingerprinting.letterboxing:true --arg https://git-scm.com/docs/git-config gives pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=dd74d4159c5dfa4307f663df24cf64766a4d5781&tochange=61cde6b6f2737eee00c49fb75390aff3d814f677 suggesting this was regressed by Bug 1789168.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

:emilio, since you are the author of the regressor, bug 1789168, could you take a look? Also, could you set the severity field?

For more information, please visit auto_nag documentation.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1793508 - Contain inline-size of findbar. r=dao,Gijs,aminomancer

So that its contents don't influence the automatic minimum size of the
tab panels. This matches the previous XUL layout behavior.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/01823fe27084
Contain inline-size of findbar. r=aminomancer

Comment 4

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/01823fe27084

Comment 5

[Ardelean Oana, Desktop QA [:oardelean]]

I managed to reproduce this issue on a 2022-10-02 Nightly build on Ubuntu 22 using the STR from the Description. Verified as fixed on Firefox 107.0b4(build ID: 20221023190001), Nightly 108.0a1(build ID: 20221023100414) on Ubuntu 22, macOS 12, Windows 10.