1997551 - Inconsistent scrolling speed in vertical tabs sidebar

Status: UNCONFIRMED

(Firefox :: Sidebar, defect)

Description

[Thibaut Guénédal]

Steps to reproduce:

Tested on Firefox 144 and Firefox Nightly 146.0a1

• Turn on Vertical tabs
• Have enough tabs open that the sidebar overflows
• Scroll the vertical tabs sidebar

Actual results:

The scrolling speed and acceleration in the tab sidebar is different from other parts of the browser such as pages, history sidebar, context menus...

Expected results:

Scrolling should be consistent across the entire browser.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Firefox::Sidebar' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Hello, thank you for the bug report!
Unfortunately I could not reproduce your issue. On my end, scrolling seems consistent for both vertical tabs/sidebar and other elements such as history/webpages. Would you be so kind as to answer a few questions so we can investigate this further?

• If possible, could you please attach a screen recording of the different scrolling behaviours?
• Does this issue happen with a new profile? Here is a link on how to create one: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles
• Does this issue happen with latest nightly? Here is a link from where you can download it: https://www.mozilla.org/en-US/firefox/channel/desktop/
• Does this issue happen when Firefox is in Troubleshoot Mode? Here’s a link on how to enable it: https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-troubleshoot-mode

Thank you.

Comment 3

[Thibaut Guénédal]

Attachment: Screencast From 2025-11-03 13-17-14.mp4

Recording on Firefox Nightly 146.0a1 in a new profile in troubleshoot mode showcasing the difference in scroll speed between vertical tabs and a web page, as well as the following settings affecting the two independently:

• general.smoothScroll
• toolkit.scrollbox.smoothScroll