Intent to Ship: Fluent Scrollbars.

[Chromestatus]

Contact emails

ara...@microsoft.com, gas...@microsoft.com

Explainer

None

Specification

None

Summary

This feature modernizes the Chromium scrollbars (both overlay and non-overlay) on Windows and Linux to fit the Windows 11 Fluent design language. Non-overlay Fluent scrollbars will be enabled by default in Linux and Windows. This change applies to Linux as well because Chromium's Linux scrollbar design has historically been aligned with what ships on Windows. How to expose enabling overlay Fluent scrollbars is still being decided. Visual spec: https://docs.google.com/document/d/1haDpb1QIh2PaLwsQD1i4WHFq_5_jSK3XK9lhgSs4WkM/edit?usp=sharing Design doc: https://docs.google.com/document/d/1GCmz2nbJV1XiopoLHnlrVaHCjhQMdiyDfPN_a22OIjU/edit?usp=sharing Intent to implement: https://groups.google.com/a/chromium.org/g/blink-dev/c/SomQdLx6aEk

Blink component

Blink>Layout>Scrollbars

Search tags

fluent, scrollbars, fluent scrollbars

TAG review

N/A

TAG review status

Not applicable

Risks

Interoperability and Compatibility

Fluent scrollbars are thinner than the existing design for them. On 100% scale, chromium scrollbars are 17px wide while Fluent scrollbars are 15px wide. This change could have the following consequences: - Some scrolling or layout tests may see a decrease in performance due to a larger viewport being rendered. - The rendered area for pages with scrollbars will be slightly larger, which may cause layout shifts for webpages who wrote their pages assuming the previous scrollbar dimensions. Here are some considerations that reduce the mentioned risks: - Platforms with overlay scrollbars enabled by default (ChromeOS, mobile devices, Mac without a mouse) already have different viewport widths for the same window size. - Scrollbars can already have different widths in different User Agents. For example, Mac's always-on scrollbars are 14px wide, and Opera GX's are 15px wide.

Gecko: N/A

WebKit: N/A

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

None

Debuggability

None

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

No

This feature is only available on Windows and Linux.

Is this feature fully tested by web-platform-tests?

No

This feature updates the design of chrome's scrollbars and doesn't modify any web API. The changes in layout are included in all tests that show scrollbars, due to the nature of how WPT evaluates results. Fluent scrollbars are already enabled by default in tests, and only a test that checked fonts was rebased because it relied on a screenshot that showed scrollbars (wpt/html/syntax/charset/without-inheritance.html).

Flag name on about://flags

FluentScrollbar

Finch feature name

FluentScrollbar

Requires code in //chrome?

False

Tracking bug

https://bugs.chromium.org/p/chromium/issues/detail?id=1292117

Availability expectation

This feature is expected to be available in Chromium stable 133, which will launch around February 2025.

Estimated milestones

DevTrial on desktop

133

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

None

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5693137379917824?gate=5830848805339136

Links to previous Intent discussions

Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/448ca565-e38e-43f0-8cb8-838db18d30d0n%40chromium.org

This intent message was generated by Chrome Platform Status.

[Domenic Denicola]

LGTM1.

I think it's a bit unclear whether or not this requires an Intent to Ship and API owner approval, but I'm supportive of the conservative path you've taken of sending one and requesting such approval.

The analysis about interop and compat that you've provided shows that there are indeed web-observable effects, but also that they should hopefully be manageable. Even if sites are specifically targeting Windows/Linux Chrome's 17px size, the most likely "breakage" is adding an extra 2px margin to such pages, which is not serious. And, if something unanticipated happens, we can always use the Finch kill-switch.

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[Mike Taylor]

LGTM2

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra_k13PBcXD53WFwiu%2BQYD6V42J5tC5jO7AQLA2meVjMhQ%40mail.gmail.com.

[Chris Harrelson]

LGTM3

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/ad3ad5a3-a10f-414a-9b64-4759639634dc%40chromium.org.