I have a bunch of groups with items in them with the exception of the last one which contains a tree.  I set the container height to something meaning full but I would like to be able to expand/contract the conatiner height so that the last group containing the tree takes up the rest of the explorer bar.   I assume I would need to do this anytime a group is expanded (or collapsed), items are added/deleted or the explorer bar gets a resize event.

What properties can I inspect to calculate the new container height at runtime?