Reflection proposal: Expose internal elements to be referenced from the outside

[mrego]

I'm not a fan of the name "Cross-root ARIA Reflection" that's why the title of the issue is longer than expected. I think it can be confused with ARIA attribute reflection and be misleading in some situations.

The problem is that you want to make a relationship between something that is in a shadow tree and something from outside the shadow tree, somehow exposing/exporting/reflecting that information outside of the Shadow DOM.

Anyway this issue is to discuss what's the best approach to solve this issue. In the explainer we're describing a few options. Let's discuss them here.

Once we agree on a proposal we can bikeshed about the best name and syntax for it.

[annevk]

I wonder how many use cases we have outside of label for going in both directions. Perhaps if we address labels semantically with a FACE proposal we can sidestep that use case entirely.

[annevk]

And even for labelledby, if the custom element points to the delegated labelledby element and custom element itself has a labelledby relationship of some kind, could that be enough?

I guess the question is whether the custom element can be both the target and originator of a labelledby pointer and that seems highly implausible.

[nolanlawson]

@mrego Is your main concern with the name "reflection"? In the explainer, this is sometimes called "exporting."

[mrego]

@mrego Is your main concern with the name "reflection"? In the explainer, this is sometimes called "exporting."

The name is confusing to me, as I think about ARIA attribute reflection when I read it; and this is something else. And yeah I guess that's why the explainer uses a different name in some parts. Anyway it would be nice to agree on a good name for this.