1971941 - [Ubuntu] Horizontal line displayed above Navigation Bar when Vertical tabs are ON

Status: VERIFIED FIXED

(Toolkit :: Startup and Profile System, defect)

Description

[Simona Badau, Desktop QA]

Attachment: Screen recording with the issue

Found in

• Nightly 141.0a1

Affected versions

• Nightly 141.0a1

Tested platforms

• Affected platforms: Ubuntu 25.04,
• Unaffected platforms: macOS 14, Windows 11.

Preconditions

• Ensure browser.profiles.enabled is set to true.
• At least one switchable profile exists (Profile A) with the Vertical Tabs and Show Sidebar options checked in about:preferences.

Steps to reproduce

1. On Profile A enter edit mode via Hamburger menu -> Profile A -> Edit.
2. Select different themes and observe the upper side of the window.

Expected result

• The themes should be set correctly, and the UI should display without any visual artifacts.

Actual result

• A horizontal line appears above the navigation bar. Please see the screen recording for more details.

Regression range

• not a regression.

Additional notes

• The issue is not reproducible when the Light, Dark or System themes are set, but is is reproducible with all the other themes.

Comment 1

[Stuart Colville [:muffinresearch]]

Hi Emilio, I wondered if you might have thoughts on this bug?

Comment 2

[Emilio Cobos Álvarez [:emilio]]

Attachment: Bug 1971941 - Fix tabs-hidden usage for navbar separator. r=#theme

tabs-hidden is set on the toolbox.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/bc26fd004257
https://hg.mozilla.org/integration/autoland/rev/d17d3b507708
Fix tabs-hidden usage for navbar separator. r=desktop-theme-reviewers,dao

Comment 4

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/d17d3b507708

Comment 5

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

The patch landed in nightly and beta is affected.
:emilio, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox141 to wontfix.

For more information, please visit BugBot documentation.

Comment 6

[Emilio Cobos Álvarez [:emilio]]

Comment on attachment 9497467 [details]
Bug 1971941 - Fix tabs-hidden usage for navbar separator. r=#theme

Beta/Release Uplift Approval Request

• User impact if declined/Reason for urgency: comment 0
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: Yes
• If yes, steps to reproduce: comment 0
• List of other uplifts needed: none
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Trivial CSS tweak.
• String changes made/needed: none
• Is Android affected?: No

Comment 7

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/20ed3a74f8bc
https://hg.mozilla.org/releases/mozilla-beta/rev/5c409af77460

Comment 8

[Peter Magyari (Desktop QA)]

Verified fixed on Ubuntu 24.10 using Nightly 142.0a1 (20250701155448).

Comment 9

[Peter Magyari (Desktop QA)]

Also verified fixed on Beta 141.0b5 (20250701171243).