[Popup] [Dialog] Evaluate which popup-related primitives should be extended to other elements

[melanierichards]

This discussion should come later on in popup incubation once popup-related primitives are more mature. We introduce a number of primitives that are necessary for popup, and we imagine that many of these would be useful in other contexts (e.g. delegatesfocus). We should go through each one and consider how these will be applicable to other elements (dialog, "all top-layer elements", or otherwise).

This also came up on MicrosoftEdge/MSEdgeExplainers#455

[github-actions]

There hasn't been any discussion on this issue for a while, so we're marking it as stale. If you choose to kick off the discussion again, we'll remove the 'stale' label.

[mfreed7]

Since this issue was opened, <popup> as an element was abandoned, and the set of features has matured significantly. I think the only potentially "more general" feature might be delegatesfocus, which likely will become a general-purpose feature that is completely separate from popup.

I'm going to close this issue.