You can hover over an editor without it being active/focused, so you may wind up listening to the wrong editor here.  But, I think it may be ok anyway.

For practical purposes, you can't modify an editor that's not focused without moving the mouse at all, so we won't miss any changes that would invalidate the popover.  We could get a false positive -- hiding a popover in one editor when a change happens in a different, focused editor.  But that doesn't seem too bad.