Here are some changes to DataGroup.
The big change is the way we instantiate components. We aren?\226?\128?\153t re-using the Group logic anymore. This means there?\226?\128?\153s no display object sharing going on, which reduces the complexity of the code. It also treats renderers differently now. Basically anytime a renderer is specified, it?\226?\128?\153ll attempt to wrap you up in that renderer, even if you are a GraphicElement or a DisplayObject and may not need one.
There are some other changes, like changing an itemRenderer at runtime now works. It?\226?\128?\153s a bit heavy in what it invalidates right now, but I?\226?\128?\153ll go back and revisit some of this logic.
Also, when no dataProvider is given, we don?\226?\128?\153t automatically create one for the user. This means I had to add some defense mechanisms where we were relying on the dataProvider, but doing a check for dataProvider != null was all that was really needed.