Change the way we handle setItemAt in DataGroup..we now do it synchronously again. However, this has the consequence that, even temporarily, you are not allowed to have the save visual element listed twice in the data collection.
Get parity with Halo behavior and Flash behavior by allowing addElement()/addElementAt() to be called on an element already in the list. When this happens just shift the indices around.
Small ASDoc fix in GroupBase. Also, change the way we handle data being set int he default complex item renderer...this way we're not using binding, and the code is also easier to understand.
QE Notes: Write tests for addElement/addElementAt on items already in the group.
Doc Notes: None
Bugs: SDK-17909, SDK-18189
tests: checkintests, mustella DataGroup, List, Group, FxContainer, FxDataContainer