Bug 283511 – AX: content ignored when double wrapped with `display: contents` within a shadow root

• Component: Accessibility
• Status: RESOLVED DUPLICATE

[Nathan Knowler]

Created attachment 473313 [details]
Labelled examples of the content being skipped and a workaround

When content is wrapped by two elements with `display: contents` within a shadow root, the content is excluded from the accessibility tree. This happens whether or not the content is interactive. A workaround is to use an element in the tree between the two elements with `display: contents`.

Example buggy HTML code:

<input value=A>
<div>
	<template shadowrootmode=open>
		<button>B</button>
		<div style=display:contents>
			<button>C</button>
			<div style=display:contents>
				<button>D</button>
			</div>
		</div>
		<slot></slot>
	</template>
	<button>E</button>
</div>
<button>F</button>

The keyboard navigation tabs through the elements in the correct (alphabetical order), but VoiceOver skips the button labelled “D.”

I’ve observed this bug on the following OS versions:

- macOS 15.1.1 (24B2091) with Safari 18.1.1 (20619.2.8.11.12)
- iOS 18.1 (22B83)

[Radar WebKit Bug Importer]

<rdar://problem/140363500>

[Nathan Knowler]

Created attachment 473315 [details]
Using VoiceOver to interact with the bug and workaround

I’ve attached a video example of the bug in VoiceOver.

[Nathan Knowler]

Created attachment 473316 [details]
Using keyboard navigation to interact with the example

Here’s also a video demonstration of keyboard navigation working correctly.

[Nathan Knowler]

I’m also observing this problem in Safari Technology Preview Release 207 (Safari 18.2, WebKit 20621.1.4.3) using the same macOS version as the OP.

[Tyler Wilcock]

This was fixed in STP 208 (though please let me know if you experience otherwise) by this change:

https://github.com/WebKit/WebKit/pull/35430 (AX: Default to walking the DOM rather than the render tree when building the accessibility tree)

[Nathan Knowler]

Yes, it looks like it is fixed in STP 208. Thanks!

[Tyler Wilcock]

*** This bug has been marked as a duplicate of bug 281749 ***