Luke Warlow

Has there been discussion on how this would apply to arrow key navigation (ala OpenUI Focusgroup or a more real example customisable select's option picker)?

> Good question! In an ideal world, it would be great if we can just put `` and everything is done. Focusgroup is still in incubation though, so we can’t...

~~Fwiw the reason it's currently on Document is just to match the other cssom-view functions which are also all scoped to Document. If this were added to DocumentOrShadowRoot it would...

I've made a PR to switch to using DocumentOrShadowRoot as it turns out that's what browsers *actually* use already.

Hmm I don't think there is currently, but a beforetoggle/toggle events for combobox select seems pretty reasonable.

Select doesn't have any events currently. Technically you could poll for :open matching or not but that's far from ideal.

The use case is to not need a single root element in shadow roots to use `:has()` in this case the root has two root elements, a button and a...

`:host:has(:popover-open) button {background: yellow;}` doesn't set the buttons background to yellow. I can only assume `:host:has()` counts as shadow piercing and so doesn't work?

Does it actually need any opt in? Can't it just be that its role is menu when it contains a new menuitem element? Likewise deal with rendering changes based on...

I'm not sure this is actually an issue in the Trusted Types spec per se. More a CSP issue in general. Because all of them are defined by strict grammars...