Bug 230438 - WKWebview sticky element with overflow scroll/auto causes elements to disappear during overscroll
Summary: WKWebview sticky element with overflow scroll/auto causes elements to disappe...
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: CSS (show other bugs)
Version: Other
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2021-09-17 18:29 PDT by Pete Lada
Modified: 2021-09-30 05:05 PDT (History)
5 users (show)

See Also:


Attachments
Example html which repros the issue (438 bytes, text/html)
2021-09-20 13:31 PDT, Pete Lada
no flags Details

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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>