The spark List has scrolling and drag + drop support built in, could you use that instead of a DataGroup and Scroller?
I made some testes but some problems appeared when I use spark:List. First because, I have a hierachical list, so I use many datagroup inside datagroup, so If I use List as render of another list I have de configure drag and drop for each of this component and in my bussines logic i cant configure drag and drop for the entire list, only some items renderes that is allowed to be dragged, so, when I configure the drag and drop only for some items renderes the scroller of the List doesn't work. In another words, I suppose that spark:List is too simple for my required interface!
I'm not sure I understand, but you can control the scroll position of the DataGroup via the horizontalScrollPosition/verticalScrollPosition properties. You might have some logic that detects when the mouse is near the top or bottom of the DataGroup and start changing the scroll position accordingly.