Accessibility guidance

[bathos]

When using this feature, developers will be implementing the draggable titlebar area and its content. However I don’t think WAI-ARIA currently provides any guidance or requirements for what implementation of a window’s titlebar entails. I may be incorrect about this — I’m not really sure what to look for. So far I haven’t found evidence of aria addressing this UI concept at all, though. For example there appears to be no aria role that maps to the ROLE_SYSTEM_TITLEBAR on Windows.

If there’s already an appropriate existing HTML or HTML+aria pattern we should be following, it would be helpful to know what it is. I think this should be included or referenced within the specification text if possible when the time comes. (And if there isn’t already an appropriate pattern or there’s missing API surface here, it might be important not to begin unflagging the API until that’s resolved?)

Unrelated general “user feedback”: I’ve been having lots of fun playing with this today! Very exciting to see it come together in chrome canary. I can report that the env vars, a bit of calc(), and grid seem to account for responsive layout needs really nicely. The only thing which seems missing to me is a media query; if I could use a query in the same manner as (display-mode: standalone), I’d need literally no JS for the title-respecting layout — CSS would account for everything.