This doesn't quite fix all the problems, as the outer editor doesn't get callbacks
when the position changes in the inner editors (and the inner ones aren't propogating
the callbacks currently) so the "n/m matches" display doesn't update properly in that
case. Also, it doesn't (yet) try to draw the search bubbles for embedded editors
Still, progress has been made; at least the bar is not red anymore when there are
hits only in embedded editors
closes PR 12786
28ca7c6d14