Bug 225034

Summary:	Exclude creating a containing block for document root element (<html>) on will-change: filter/backdrop-filter
Product:	WebKit	Reporter:	Tim Nguyen (:ntim) <ntim>
Component:	Layout and Rendering	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	ahmad.saleem792, bfulgham, gsnedders, simon.fraser, webkit-bug-importer, zalan
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	Unspecified
OS:	Unspecified
URL:	http://wpt.live/css/css-will-change/will-change-fixedpos-cb-003.html
See Also:	https://bugs.webkit.org/show_bug.cgi?id=243571

Description Tim Nguyen (:ntim) 2021-04-25 12:34:49 PDT

will-change: filter/backdrop-filter should not create a containing block on the root element.

WPT: https://webkit-search.igalia.com/webkit/source/LayoutTests/imported/w3c/web-platform-tests/css/css-will-change/will-change-fixedpos-cb-003.html

Spec: https://drafts.fxtf.org/filter-effects/#FilterProperty

> A value other than none for the filter property results in the creation of a containing block for absolute and fixed positioned descendants unless the element it applies to is a document root element in the current browsing context. The list of functions are applied in the order provided.

Comment 1 Simon Fraser (smfr) 2021-04-26 09:25:39 PDT

The root is always a containing block so I'm confused by this bug.

Comment 2 zalan 2021-04-26 09:39:49 PDT

(In reply to Simon Fraser (smfr) from comment #1)
> The root is always a containing block so I'm confused by this bug.
I looked at the test case and apparently the root here means the <html> element and not the Initial Containing Block.
Please rename the bug.

Comment 3 Radar WebKit Bug Importer 2021-05-02 12:35:12 PDT

<rdar://problem/77437740>

Comment 4 Sam Sneddon [:gsnedders] 2022-08-05 10:22:24 PDT

*** Bug 243571 has been marked as a duplicate of this bug. ***