Bug 260443

Summary: Kinetic scrolling stops after elements are slotted
Product: WebKit Reporter: Steve Orvell <steveorvell>
Component: ScrollingAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari 16   
Hardware: iPhone / iPad   
OS: iOS 16   
Attachments:
Description Flags
Scrolling freezes after scrolling horizontally inside the top bordered container on iOS/iPadOS none

Steve Orvell
Reported 2023-08-20 06:31:53 PDT
Created attachment 467346 [details] Scrolling freezes after scrolling horizontally inside the top bordered container on iOS/iPadOS Setup: 1. An element has a shadowRoot with a <slot> in it. 2. The element is scrollable. 3. A child element is appended and slotted to the <slot> *while* the element is scrolling. Expected: * The element continues to scroll after the child is appended. Actual: * The element immediately stops scrolling after the child is appended. Reproduction: * Scroll horizontally inside each bordered container. * Note, this issue occurs only on iOS/iPadOS. The attached reproduction shows the *incorrect* behavior when a child is appended and slotted, and it also shows the *expected* behavior when a child is appended to the shadowRoot itself rather than slotted. The reproduction is also available at https://lit.dev/playground/#gist=05deaacf5ba04c069cc41b9d523b636b&view-mode=preview.
Attachments
Scrolling freezes after scrolling horizontally inside the top bordered container on iOS/iPadOS (1.84 KB, text/plain)
2023-08-20 06:31 PDT, Steve Orvell 		no flags
Details
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Simon Fraser (smfr)
Comment 1 2023-08-21 09:50:42 PDT
Does this happen with equivalent DOM mutations that don't involve slots?
Steve Orvell
Comment 2 2023-08-21 09:53:00 PDT
No, when the mutation does not involve slotting, scrolling works as expected. See the explanation of the repro at the end of the initial report.
Radar WebKit Bug Importer
Comment 3 2023-08-27 06:32:12 PDT
<rdar://problem/114523840>
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