Update Understanding Focus Not Obscured

[bruce-usab]

Closes Issue #2809

WRT to diff — look at (Minimum) version first

• Understanding Focus Not Obscured (Minimum) has relatively few changes as compared to the previous version.
• Understanding Focus Not Obscured (Enhanced) started from (Minimum) version in this PR, so diff looks like a complete rewrite.

[bruce-usab]

After backlog call 5/5, I noticed another place parenthetical needed.
I added (Enhanced) version to this PR.

[bruce-usab]

Added @mbgower to review since he was feeling caught up.

Should (Enhanced) version be so tolerant of opaque overlay?

[bruce-usab]

Edit to (Enhanced) version after AGWG call 5/9.

[mbgower]

Should (Enhanced) version be so tolerant of opaque overlay?

Actually, @bruce-usab, on re-reading the Enhanced normative text, I do not believe that a lightbox should be considered to fail this criteria. The language does not use "obscured", it uses "hidden".

no part of the component is hidden by author-created content.

I don't think we can make the case that dimming something hides it. Even in the minimum version, we don't say the lightbox is failing Focus Not Obscured. We say it is likely to fail 2.4.11 Focus Appearance.

On rereading that part of the Minimum understanding document, I have some changes to suggest.

1. Given that 2.4.11 is now a AAA, my feeling is that the language in the minimum should actually point to Non-text contrast, and
2. the Enhanced version should point to Focus Appearance.

That gives us something appropriate to assess at each of the levels. If you agree, can you alter this PR to support that?

As part of that, you will need to remove this commit: 61dcd0c

At that point, the language for Enhanced seems fine for lightbox (assuming the link points to the AAA version of Focus Appearanced). The AA version would need to be updated.

[bruce-usab]

@mbgower I think the root problem is that there is a bit of a disconnect between the SC name and text. because hidden is a little bit stronger than obscured. A light box certainly obscures. But does it hide?

Ping to @alastc since I think we might actually need an AGWG survey to resolve this.

Also maybe the text of Focus Not Obscured (Enhanced) AAA — and only Enhanced not (Minimum), AA — might be adjusted?

When a user interface component receives keyboard focus, no part of the component is obscured hidden by author-created content.

[bruce-usab]

@mbgower wrote:

That gives us something appropriate to assess at each of the levels. If you agree, can you alter this PR to support that?
....
As part of that, you will need to remove this commit: 61dcd0c

I am doing a new PR (and separate issue) for these details.

[alastc]

Approved: https://www.w3.org/2023/05/16-ag-minutes#item06