Bug 236585 – Safari moves focus to first focusable element inside an element with role="dialog" and aria-modal="true" when added to the DOM

• Component: Accessibility
• Status: RESOLVED FIXED

[Alex Moore]

Created attachment 451883 [details]
Test Case

All Platforms - iOS (15.3) and MacOS 

Adding an element with the attributes role="dialog" and aria-modal="true" containing focusable elements causes the first of these elements to receive focus. This is not the behaviour of Firefox or Chrome, and causes compatibility issues. 

Related bugs (possibly over-specific): https://bugs.webkit.org/show_bug.cgi?id=211934

See the test case. Reproduce by clicking the button to add the element with role="dialog" and aria-modal to the DOM. See the button inside the element receive focus.

[Radar WebKit Bug Importer]

<rdar://problem/88897436>

[Tyler Wilcock]

Thanks for the bug report!

It's implemented this way due to this language in the aria-modal spec (though WebKit's autofocus behavior will currently also apply to <dialog>):

https://w3c.github.io/aria/#aria-modal

> When a modal element is displayed, assistive technologies SHOULD navigate to the element unless focus has explicitly been set elsewhere.

Technically, with that wording it should be VoiceOver (and other assistive technologies) doing this automatic focusing, but WebKit does this itself for now.

I do understand how this could be annoying when other browsers don't do this. And it would definitely be a bug if this autofocus behavior is trouncing explicit focus via JS or otherwise.

[Alex Moore]

It seems that the focus isn't moved anymore in either Safari TP or iOS 15.5 beta, so something must have changed the behaviour, as it now matches the other browsers. 

It might be due to another bug though, as Safari TP seems to struggle with the page, and it crashes and then needs to reload it as soon as you try to inspect it. See the attached screenshot.

[Alex Moore]

Created attachment 459109 [details]
Crash message after inspect

Crash message after inspect

[Alex Moore]

Edit: Only changed in Safari TP, not iOS.

[Tyler Wilcock]

The crash you're experiencing will be fixed by https://bugs.webkit.org/show_bug.cgi?id=240365 (Infinite recursion caused by call to accessibilityIsIgnored in the midst of AccessibilityObject::ignoredFromModalPresence). With this change in place, I can confirm that the latest `main` WebKit does still autofocus with your testcase.

[Tyler Wilcock]

Pull request: https://github.com/WebKit/WebKit/pull/38735

[EWS]

Committed 288641@main (71b1107b4656): <https://commits.webkit.org/288641@main>

Reviewed commits have been landed. Closing PR #38735 and removing active labels.