Make destroyDescendants() just work on this.containerNode, so that embedded widgets like FloatingPane's resize handle don't get destroyed by doing FloatingPane.setContent(). Added this._supportingWidgets attribute to hold widgets created as part of template, so they can be destroyed when the main widget is destroyed.   In the future could also leverage this._supportingWidgets to hold other supporting widgets like FloatingPane's resizeHandle or TabContainer's tab list. Fixes #5865. (!strict to avoid spurious warnings about nested function)
Make destroyDescendants() just work on this.containerNode, so that embedded widgets like FloatingPane's resize handle don't get destroyed by doing FloatingPane.setContent().
Added this._supportingWidgets attribute to hold widgets created as part of template, so they can be destroyed when the main widget is destroyed.   In the future could also leverage this._supportingWidgets to hold other supporting widgets like FloatingPane's resizeHandle or TabContainer's tab list.
Fixes #5865.
(!strict to avoid spurious warnings about nested function)

git-svn-id: ee6e786acc44c9cca5ee17c71a5576c45c210361@12726 560b804f-0ae3-0310-86f3-f6aa0a117693

redaktor/deliteful