Bug 230438

Summary:

WKWebview sticky element with overflow scroll/auto causes elements to disappear during overscroll

Product:

WebKit

Reporter:

Pete Lada <pklada>

Component:

CSS

Assignee:

Nobody <webkit-unassigned>

Status:

NEW ---

Severity:

Normal

CC:

kevin_neal, knneth+webkit, mrobinson, simon.fraser, webkit-bug-importer

Priority:

Keywords:

InRadar

Version:

Other

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
Example html which repros the issue	none

Description Pete Lada 2021-09-17 18:29:03 PDT

This doesn't seem to happen in mobile safari, only reproducible in a WKWebView. If I have a sticky element which is either itself set to overflow:scroll/auto or has a child with the same overflow rules, any child of those elements disappears during overscroll. They seem to disappear at the same moment that their container would otherwise have scrolled out of view (but is still visible due to being sticky). Note this doesn't happen with position: fixed elements, only position: sticky. 

Here is a video of the behavior: https://share.getcloudapp.com/jku40OLl

The markup is relatively simple. A sticky positioned element, inside a div with overflow set to "auto" and white-space to "nowrap" so that the container is forced to scroll. Note that if the content doesn't actually force a scroll the bug doesn't seem to occur. 

Thanks

Comment 1 Simon Fraser (smfr) 2021-09-20 09:59:56 PDT

Could you please attach an HTML file with the markup that reproduces this? Thanks.

Comment 2 Pete Lada 2021-09-20 13:31:20 PDT

Created attachment 438720 [details]
Example html which repros the issue

Comment 3 Pete Lada 2021-09-20 13:35:40 PDT

Video of repro w/ attached markup https://share.getcloudapp.com/GGupbKPE

Comment 4 Radar WebKit Bug Importer 2021-09-21 10:28:27 PDT

<rdar://problem/83357927>