1739154 - delegatesFocus changes focused inner element when host is focused

Status: RESOLVED FIXED

(Core :: DOM: UI Events & Focus Handling, defect)

Description

[Nolan Lawson]

Attachment: Screen Shot 2021-11-03 at 8.39.20 AM.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36

Steps to reproduce:

1. Go to this URL: https://bl.ocks.org/nolanlawson/ef0cebcb48a5cf958d176056486642cd

Actual results:

It says "focused: first" and the first input is focused.

Expected results:

It should say "focused: second" and the second input should be focused.

As shown in the attached screenshot, Chrome 95 and Safari 15.1 have the correct behavior.

It also seems to depend on whether the focusable elements are inside an iframe. Here is a demo without an iframe – all three browsers correctly say "focused: second" in this case: https://bl.ocks.org/nolanlawson/ef0cebcb48a5cf958d176056486642cd

The key part of the code is this:

div.shadowRoot.querySelector('.second').focus()
div.focus()

Because div is a shadow host with delegatesFocus set to true, focusing it should not change the focus from the second input to the first input.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::DOM: UI Events & Focus Handling' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[Emilio Cobos Álvarez [:emilio]]

https://bl.ocks.org/nolanlawson/raw/ef0cebcb48a5cf958d176056486642cd/?raw=true shows second on Nightly

Comment 3

[Nolan Lawson]

Sorry, I made a typo with the URLs I provided.

• Iframe: https://bl.ocks.org/nolanlawson/ef0cebcb48a5cf958d176056486642cd
• No iframe: https://bl.ocks.org/nolanlawson/raw/ef0cebcb48a5cf958d176056486642cd/?raw=true

On my machine (MacOS Big Sur 11.6), I get the following results:

	Firefox Nightly 96.0a1	Firefox 94.0
Iframe	first (incorrect)	first (incorrect)
No iframe	second (correct)	second (correct)

I.e., both versions behave the same (incorrectly) in the version with the iframe. Both are also correct for the version without the iframe.

Comment 4

[Sean Feng [:sefeng211]]

When the document is an embedded iframe, this check fails because the browsing context isn't a top level browsing context, and this makes the behaviour different.

Looks like I probably incorrectly interpreted the spec. I am making a patch to fix that.

Comment 5

[Sean Feng [:sefeng211]]

Attachment: Bug 1739154 - Fix a bug where focus delegate step may be run when it shouldn't be r=emilio

According to the spec, focus delegate step should be run unless
the focus target is a shadow-including-ancestor of the current focus.
Our code didn't do this correctly.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ce9573bfe078
Fix a bug where focus delegate step may be run when it shouldn't be r=emilio

Comment 7

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/32740 for changes under testing/web-platform/tests

Comment 8

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/ce9573bfe078

Comment 9

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot