[BUG #8560] listen for addedChild/removedChild events instead of updateLayout
[BUG #8560] store animation properties on the page
[BUG #8560] dispose child widgets
[BUG #8560] moved default transition animation to the page
[BUG #8514] removed obsolete tests
[BUG #8560] doc fixes
[BUG #8560] updated tests