Consider allowing aria-hidden=false on visibly rendered elements inside an ancestor with aria-hidden=true #1256

In relation to aria-hidden error cases #1254 and #1255, @aleventhal suggested that we reconsider allowing aria-hidden=false on visibly rendered elements inside an ancestor with aria-hidden=true

The example of this is aria-hidden=true on a main section, but aria-hidden=false to "unhide" the descendant, such as a dialog or menu. In this case, the WG generally agreed that the author intention is pretty clear.

<main aria-hidden="true">
  ... main content hidden during this state, and usually "grayed out" visually ...
  <div role="menu" aria-hidden="false">
      ... dialog or menu content "unhidden" ...
  </div>
</main>

It's worth noting that, years ago, @asurkov was opposed to having aria-hidden="false" expose non-rendered elements to the accessibility tree, and I think in most cases that concern is still valid. This issue is proposing that visible, rendered elements could use this pattern... somewhat similar to a non-inert descendant of an inert ancestor.

Opening for discussion. @aleventhal suggested both @asurkov and @jcsteh may have comments.