1921190 - Vertical tabs scrollbar is offset from the sidebar edge and harder to see

Status: RESOLVED DUPLICATE of bug 1910358

(Firefox :: Sidebar, defect)

Description

[Kestrel]

Attachment: Scrollbar offset from sidebar edge on Ubuntu 24.04

STR:

1. Start with sidebar.verticalTabs = true and sidebar.revamp = true.
2. Create many tabs (Ctrl+T) so the list overflows and the scrollbar thumb becomes small.
3. Try scrolling to opposite ends of the tab list by clicking inside the scrollbar track.

Expected:
Scrollbar sits on edge of sidebar border.

Actual:
Scrollbar floats next to tabs, offset from the edge of the sidebar. Determining if the cursor is inside the scrollbar track on Ubuntu 24.04 takes some guesswork as only the thumb thickness increases slightly when hovered. Scrollbars that sit on the edge of a clearly defined border do not have this issue.

Windows 11 scrollbars have better track visibility but it still requires some hunting instead of just clicking on the edge of the sidebar.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=7c7c002d7db21d21cbef7f1e16c189e648b6d230&tochange=57667e89d7829978215a88bf55edf27fbda94c72

Regressed by Bug 1902083.

Comment 1

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

:tgiles, since you are the author of the regressor, bug 1902083, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 2

[Tim Giles [:tgiles] | OOO May 28 - May 31]

Thanks for filing this! This is fixed as part of Bug 1910358, so will mark this as a dupe.