Expand/collapse control present under 'Participants' are not accessible using keyboard in windows.

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Test Environment:
OS Build: 25H2 (OS Build 26200.5670)
Browser: Edge version 139.0.3394.0 (Official build) (64-bit)
URL: https://visjs.github.io/vis-timeline/examples/timeline/groups/nestedGroups.html

User Impact:
Keyboard navigation users will be impacted, and they will not be able to use the Expanded/Collapsed control functionality as Expand/collapse control present under "Participants" are not accessible using keyboard in windows.

Repro Steps:

1. Open URL: https://visjs.github.io/vis-timeline/examples/timeline/groups/nestedGroups.html in latest edge browser.
2. Press tab key to navigate on the page.
3. Verify whether Expand /collapse control present under "Participants" are not accessible using keyboard in windows or not.

Actual Result:
While navigating using keyboard tab/ shift tab key, keyboard focus is not moving to Expand/collapse control.

Refer Attachment:
1.Expand & collapse control present under 'Participants' are not accessible using keyboard in windows.png
2.Expand & collapse control present under 'Participants' are not accessible using keyboard in windows.mp4

https://github.com/user-attachments/assets/af1a8df6-aaf5-4c86-a74c-6aa0c03363a3

Expected Result:
While navigating using keyboard tab/ shift tab key, keyboard focus should move to Expand/collapse control and it should be accessible on pressing enter/space key.

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Hi Team, Any update on this issue?

[msftedad]

Hi Team, Any update on this issue?