Intermediate checkin for !StackContainer to stop using deprecated this.subscribe().  In a later checkin I'd like to get rid of using topics altogether.   Also need to stop using deprecated synthetic keypress event.  Refs #16585 !strict.
Intermediate checkin for !StackContainer to stop using deprecated this.subscribe().  In a later checkin I'd like to get rid of using topics altogether.   Also need to stop using deprecated synthetic keypress event.  Refs #16585 !strict.

git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@30468 560b804f-0ae3-0310-86f3-f6aa0a117693

redaktor/deliteful