Bug 192877

Summary: user scrollable overflow causes behavior "as-if-positioned" lifting itself higher in paint order than if not overflowing
Product: WebKit Reporter: jonjohnjohnson <hi>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
animating scrollable content to expose paint order bug none

jonjohnjohnson
Reported 2018-12-19 14:05:23 PST
Created attachment 357723 [details] animating scrollable content to expose paint order bug Can't seem to find a webkit bug tracking this, though it is seemingly known among vendor developers (https://github.com/w3c/csswg-drafts/issues/2717#issuecomment-395911418) 1. Open the attached case. 2. Watch overflow:auto box that has green content grow and shrink, creating and removing user scrollable content every 2 seconds. 3. See that when it overflows, it behaves as-if-positioned painted higher and lower in order than the red block (which also is always lifted higher because of overflow). Compat Firefox doesn't let "user scrollable" overflow affect paint order, red block is always behind green in test case. Blink has same/similar issue, but is working on fix??? https://bugs.chromium.org/p/chromium/issues/detail?id=370604#c_ts1545253494 *I say user scrollable, because overflow:hidden doesn't create compositing order issue
Attachments
animating scrollable content to expose paint order bug (937 bytes, text/html)
2018-12-19 14:05 PST, jonjohnjohnson 		no flags
Details
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Radar WebKit Bug Importer
Comment 1 2018-12-20 16:23:21 PST
<rdar://problem/46887177>
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