AX: List structure does not get communicated when arrowing within `contenteditable`

• Component: Accessibility
• Status: NEW ---

[Ben Cronin]

Created attachment 466687 [details]
VO does not announce list structure when arrowing through contenteditable (but it does when navigating static content)

NOTE: This is similar to https://bugs.webkit.org/show_bug.cgi?id=248179, but different in that navigation is done by plain arrow keys (w/o VO modifier), which is the way many users are expected to move through `contenteditable`.

List structure does not get communicated when arrowing through `contenteditable` areas.

Reproduction Steps:
1. Turn on VoiceOver
2. Go to https://codepen.io/spanage/pen/XWYZmWe
3. Navigate to the first area using VO.
4. Navigate through the contents using arrow keys (w/o VO modifier, this is a standard way of navigating text). Notice the list is read, "bullet coffee, bullet tea, white bullet black" etc.
5. Navigate to the second area using VO.
6. VOKeys + Shift + Down Arrow into Area 1 and use VOKeys + Right arrow to navigate thru the contents. Notice that VO handle the list as expected, reporting items counts, level, etc.

Expected: VO indicates list information in contenteditable areas as it does in on Chrome using either JAWS or NVDA version is 2022.3.2.

Attached - video of bug repro on:
Safari Version 16.5 (also affects Chrome and Firefox)
MacOS 13.4

Impact: Screen reader users are not aware of the presence/structure of lists within the Quip and Slack editors (and lists are one of the most common/fundamental content types used within those editors).

[Radar WebKit Bug Importer]

<rdar://problem/110741492>