Re: [w3ctag/design-reviews] Beforematch event and content-visibility: hidden-matchable (#511)

@kenchris, @alice and myself took another pass reviewing the final proposal of the feature during our "Kronos" VF2F. 
Overall we are happy with the current design being a CSS property instead of HTML attribute. The functionality is similar to `display:none` if we were to add an optional `matchable` value and make it apply to the contents of the element and not the element itself.

One important question that came up during the review is whether we have verified that this new way of making content hidden is handled correctly per the [Name Computation](https://www.w3.org/TR/accname-1.1/) algorithm. Since this feature makes content hidden our expectation is that the behavior will be similar to that of `diaplay:none` and we ask that you consider adding a WPT test to cover that scenario.

Specifically, that an `aria-labelledby` or `aria-describedby` attribute which refers to an element within a `content-visibility: hidden`, `content-visibility: auto` or `content-visibility: hidden-matchable` block will correctly expose the text of the element as contributing to the name/description of the referring element:

```html
 <input aria-labelledby="a-label">
 <div style="content-visibility: hidden-matchable">
   <span id="a-label">This should be the label of the above input</span>
 </div>
```

Thank you for working with us.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3ctag/design-reviews/issues/511#issuecomment-767932845