Bug 230438

Summary: WKWebview sticky element with overflow scroll/auto causes elements to disappear during overscroll
Product: WebKit Reporter: Pete Lada <pklada>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: kevin_neal, knneth+webkit, mrobinson, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Other   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Example html which repros the issue none

Pete Lada
Reported 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
Attachments
Example html which repros the issue (438 bytes, text/html)
2021-09-20 13:31 PDT, Pete Lada 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Simon Fraser (smfr)
Comment 1 2021-09-20 09:59:56 PDT
Could you please attach an HTML file with the markup that reproduces this? Thanks.
Pete Lada
Comment 2 2021-09-20 13:31:20 PDT
Created attachment 438720 [details] Example html which repros the issue
Pete Lada
Comment 3 2021-09-20 13:35:40 PDT
Video of repro w/ attached markup https://share.getcloudapp.com/GGupbKPE
Radar WebKit Bug Importer
Comment 4 2021-09-21 10:28:27 PDT
<rdar://problem/83357927>
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