Bug 238617

Summary:	[iOS] Fixed elements jump when scrolling
Product:	WebKit	Reporter:	Brent Fulgham <bfulgham>
Component:	Scrolling	Assignee:	Nobody <webkit-unassigned>
Status:	RESOLVED FIXED
Severity:	Normal	CC:	bfulgham, jack, simon.fraser, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Local Build
Hardware:	Unspecified
OS:	Unspecified

Description Brent Fulgham 2022-03-31 10:53:54 PDT

Converted from a codepen.io test case:

// Just use your mouse wheel and it'll scroll at a steady pace. In Safari, as long as it's 
// in debug mode (NOT an iframe), you'll see that the fixed elements on the left/right JUMP 
// intermittently under heavy load!

You MUST open this in debug mode so that it's not in an iframe!
https://codepen.io/GreenSock/pen/ExoyEyg/c0402caac3044c3f5bb85022450b059b

Comment 1 Radar WebKit Bug Importer 2022-03-31 10:54:12 PDT

<rdar://problem/91113767>

Comment 2 Simon Fraser (smfr) 2022-03-31 12:26:13 PDT

I cannot reproduce this in iOS 15.4

Comment 3 Jack Doyle 2022-03-31 22:57:50 PDT

I was seeing it in Safari 15.3 on Mac OS

Comment 4 Simon Fraser (smfr) 2022-04-01 10:44:40 PDT

I don't see it in Safari 15.4 on macOS.

Comment 5 Brent Fulgham 2022-04-06 09:00:19 PDT

@Jack: Can you report your findings with iOS 15.4 or Safari 15.4 on macOS?

Comment 6 Jack Doyle 2022-04-07 00:42:10 PDT

It does seem significantly improved in 15.4. Good job!

Comment 7 Brent Fulgham 2022-04-13 09:41:55 PDT

(In reply to Jack Doyle from comment #6)
> It does seem significantly improved in 15.4. Good job!

Thank you! Please let us know if you encounter further issues.