1804414 - Tabstrip switch-to-tab / scroll-into-view on an overflown tabstrip should not animate if the user has indicated they prefer reduced motion

Status: RESOLVED FIXED

(Firefox :: Tabbed Browser, defect, P3)

Description

[:Gijs (he/him)]

Steps to reproduce:

In Windows 10 Settings, in Display, set "Show animations in Windows" to Off.
Or on macOS, in the Accessibility system preferences, under "Display" tick the "Reduce motion" checkbox.

Alternatively, in Firefox about:config, set "ui.prefersReducedMotion" to integer 1. Restart Firefox.

Open a new tab when the tab bar is already full of open tabs and some tab early (leftward) in the list is selected.

Actual results:
The whole tab bar will glide rapidly to the new tab on the far right side.

Expected results:

The tab bar should jump instantaneously to the new tab instead of gliding.

---

It looks like the code responsible might be this bit of the arrowscrollbox code. Although we can work around this by checking for the prefers-reduced-motion media query from JS using matchMedia and altering the arguments we pass to scrollIntoView, I wonder if the DOM/layout code should be automatically not applying animated scrolling if that setting is enabled. That'd be something to take up with the DOM team - we may want to just apply a workaround in the meantime but we should still chase it as that'd improve website a11y.

Comment 1

[Cieara Meador [:cmkm]]

Attachment: Bug 1804414 - Tabstrip animation should respect OS reduced motion pref r?Gijs

Comment 2

[Cieara Meador [:cmkm]]

(In reply to :Gijs (he/him) from comment #0)

[...] I wonder if the DOM/layout code should be automatically not applying animated scrolling if that setting is enabled. [...]

Looks like this is being handled in Bug 1753565!

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2f4e4480086d
Tabstrip animation should respect OS reduced motion pref r=Gijs,emilio

Comment 4

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/2f4e4480086d

Comment 5

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

Since nightly and release are affected, beta will likely be affected too.
For more information, please visit auto_nag documentation.

Comment 6

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

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

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox110 to wontfix.

For more information, please visit auto_nag documentation.

Comment 7

[Cieara Meador [:cmkm]]

Attachment: Beta uplift request

Approval Request Comment
[Feature/Bug causing the regression]: Bug 1804414, Tabstrip animation isn't adhering to OS reduced motion pref
[User impact if declined]: Users with reduced motion pref will continue to see animation
[Is this code covered by automated tests?]: No, this fix is CSS-only
[Has the fix been verified in Nightly?]: Yes
[Needs manual test from QE? If yes, steps to reproduce]: Yes; STR in description
[List of other uplifts needed for the feature/fix]: N/a
[Is the change risky?]: Low risk
[Why is the change risky/not risky?]: This is a one-liner CSS fix affecting only scrollbox elements with smoothscroll=true attribute
[String changes made/needed]: N/a

Comment 8

[Pascal Chevrel (relman team) -> :pascalc]

Comment on attachment 9313855 [details]
Beta uplift request

Approved for 110 beta 6, thanks.

Comment 9

[Pascal Chevrel (relman team) -> :pascalc]

https://hg.mozilla.org/releases/mozilla-beta/rev/c37de1807b92

Comment 10

[Ciprian Georgiu, Desktop QA]

I have reproduced the issue on Win 10 x64 with STR from comment 0, on an affected Nightly build (2022-12-07).

The issue is verified as fixed on latest Nightly 111.0a1 and Beta 110.0b6 under Win 10 x64 and macOS 11.