Bug 293845

Summary: will-change: offset-position should create a stacking context
Product: WebKit Reporter: Ahmad Saleem <ahmad.saleem792>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: koivisto, ntim, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://github.com/w3c/fxtf-drafts/issues/609

Ahmad Saleem
Reported 2025-05-30 20:18:05 PDT
Hi Team, While going through Blink's test cases for motion path, I noticed three failures but one was about following case: Test Case Name - position-will-change-establishes-stacking-context.html Test Case Link - https://jsfiddle.net/6xkwroL0/ ^ Fails in WebKit ToT (295637@main) and Firefox Nightly 141 (20250528092647) while passes in Chrome Canary 139.0.7210.0 (Official Build) canary (arm64) . This fixes in WebkIt: > Source/WebCore/rendering/style/WillChangeData.cpp in function 'propertyCreatesStackingContext', add below: case CSSPropertyOffsetPosition: This progresses above Blink test case. Web Specification - https://drafts.fxtf.org/motion-1/#offset-position-property Just raising here to see whether we need to fix or we should as Blink to match WebKit and Firefox. Thanks1
Attachments
Sam Sneddon [:gsnedders]
Comment 1 2025-06-03 12:57:58 PDT
If we believe there's any web compat impact, we should raise a spec bug. If we don't, we could at least write a WPT test that it _doesn't_ establish a stacking context so there's some failing test, and/or file a bug against Chromium.
Radar WebKit Bug Importer
Comment 2 2025-06-06 20:19:14 PDT
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