[flexcoders] How to address relative tile in TileList in dragDrop event processing?

[Peter Connolly]

Say you have a TileList:

<mx:TileList id="tilelist1" dataProvider="{anyAC}" 
    columnCount="9" rowCount="9" dragDrop="myDragDrop(event);"/>

Now say you drop an object onto the cell at row 3, column 5, you'd
like to be able to easily address the data in position 15 in the
ArrayCollection "anyAC" when processing the 'drop' event in
"myDragDrop()". 

I've looked.  I don't see any property in the DragEvent that gives you
the relative position in a TileList.  What am I missing?