Bug 308044

Summary: Regression: Incorrect position when multiple transform transitions play at once
Product: WebKit Reporter: Martin (MConverter) <webkit.bugzilla>
Component: AnimationsAssignee: Nobody <webkit-unassigned>
Status: RESOLVED DUPLICATE    
Severity: Normal CC: graouts, webkit-bug-importer, webkit.bugzilla
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: All   
OS: All   
Attachments:
Description Flags
demo.html: Demo to reproduce the bug
none
Demo video of repro on iPhone none

Martin (MConverter)
Reported 2026-02-17 03:54:42 PST
Created attachment 478386 [details] demo.html: Demo to reproduce the bug Steps to reproduce: 1. Open the attached demo.html 2. Move the mouse over the arrow and immediately click it (or tap it if on touchscreen) 3. Wait 1-2 seconds and observe how it shifts to the left, until some next transition/layout recalculation? occurs The bug starts reproducing at some point after version 16.2. It's confirmed visible in version 17.2.
Attachments
demo.html: Demo to reproduce the bug (919 bytes, text/html)
2026-02-17 03:54 PST, Martin (MConverter) 		no flags
Details
Demo video of repro on iPhone (4.07 MB, video/mp4)
2026-02-17 03:56 PST, Martin (MConverter) 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Martin (MConverter)
Comment 1 2026-02-17 03:56:14 PST
Created attachment 478387 [details] Demo video of repro on iPhone
Radar WebKit Bug Importer
Comment 2 2026-02-17 05:35:11 PST
<rdar://problem/170544316>
Antoine Quint
Comment 3 2026-02-18 00:01:40 PST
In my testing on macOS, this progressed within this range: https://commits.webkit.org/compare/304534@main...304521@main. My guess was that this progressed with 304526@main which enabled "Blocks in inline layout (disable continuations)", and checking in STP 237 you can see the issue reproducing with that setting off, and not reproducing with that setting on. On iOS, I only tested iOS 26.4 where the issue does not reproduce either. I also tested there that this flag altered the behavior. Duping to bug 303236. *** This bug has been marked as a duplicate of bug 303236 ***
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