dhb This solves the really not elegant at all way to determine what tree item

dhb  This solves the really not elegant at all way to determine what tree item
     goes with what stacked widget item.  ( When a tree item is clicked )
     This begins the framework for being able to add and destroy tree widget
     items and associated stacked widget items on the fly.
     I still need to fix a few items such as the ability to close a window and
     never get it back, ... ever.

git-svn-id: https://bacula.svn.sourceforge.net/svnroot/bacula/trunk@4407 91ce42f0-d328-0410-95d8-f526ca767f89