[csswg-drafts] [cssom-view] element.checkVisibility() should query the flat tree not shadow-including ancestors (#9486)

nt1m has just created a new issue for https://github.com/w3c/csswg-drafts:

== [cssom-view] element.checkVisibility() should query the flat tree not shadow-including ancestors ==
https://drafts.csswg.org/cssom-view/#dom-element-checkvisibility

The spec mentions "shadow-including ancestor" multiple times, but this doesn't match CSS rendering. CSS rendering uses the flat tree, not the shadow-including tree.

This makes a difference when you involve slots. 

In fact it looks like Chrome uses the flat tree in the implementation too: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/dom/element.cc;l=9073?q=Element::checkVisibility&ss=chromium


cc @tabatkins @josepharhar @vmpstr 

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/9486 using your GitHub account


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Received on Wednesday, 18 October 2023 05:20:30 UTC