Bug 235171

Summary: REGRESSION (iOS 15): Touch position shifts upward from rendering position when changed `position` to `fixed` after scrolling down.
Product: WebKit Reporter: Nozomu Miyamoto <irregular0number>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: RESOLVED CONFIGURATION CHANGED    
Severity: Normal CC: ap, bfulgham, jonlee, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari 15   
Hardware: iPhone / iPad   
OS: iOS 15   
Attachments:
Description Flags
bugged web inspector
none
reproduction demo with iOS 14.5 none

Description Nozomu Miyamoto 2022-01-12 19:25:39 PST
Created attachment 449020 [details]
bugged web inspector

Touch position shifts 85px(about the height of the navigation bar) upward from rendering position when changed `position` to `fixed` after scrolling down.
Comment 1 Nozomu Miyamoto 2022-01-12 19:26:35 PST
iOS 15 Rendering Bug Demo
https://github.com/nontangent/ios-15-rendering-bug-demo
Comment 2 Alexey Proskuryakov 2022-01-14 16:33:08 PST
Thank you for the report! Could you please confirm if this is new with iOS 15, or if this was happening with iOS 14.x before?
Comment 3 Nozomu Miyamoto 2022-01-16 23:14:50 PST
OK. I just confirmed on iOS 14.5 simulator.
As a result, this is a new problem with iOS 15 and it was not happened with iOS 14.5  as show in the new attached picture.
Comment 4 Nozomu Miyamoto 2022-01-16 23:15:43 PST
Created attachment 449310 [details]
reproduction demo with iOS 14.5
Comment 5 Radar WebKit Bug Importer 2022-01-17 19:14:05 PST
<rdar://problem/87693262>
Comment 6 Simon Fraser (smfr) 2022-02-25 14:26:21 PST Comment hidden (obsolete)
Comment 7 Simon Fraser (smfr) 2022-02-25 14:36:25 PST
I can't reproduce this in recent builds. Are you able to try iOS 15.4 beta?
Comment 8 Nozomu Miyamoto 2022-02-28 00:37:07 PST
(In reply to Simon Fraser (smfr) from comment #7)
> I can't reproduce this in recent builds. Are you able to try iOS 15.4 beta?

Really!? It's good news!

I can reproduce this in the simulator on iOS 15.2.

Unfortunately, I can't try it on iOS 15.4-beta because I don't have the actual machine, but I will do it when it is added to the simulator.
Comment 9 Jon Lee 2022-02-28 12:46:22 PST
Marking as config changed for now, then. Please reopen if this continues to reproduce.