basically this is what your lookin for
<img src="https://dl.dropbox.com/u/53012532/SnapToDroppedOverlap.png" border="0" />
It sets the dropped objects x outside of the overlapped object but doesnt effect its y. No matter where you drop Sprite2 on Sprite itll never overlap
The main problem is its not easy (I cant figure it out) to take into account y instead of x. Like to place it above or below but on the same x. You cant do both cause itll always be angled to the edge regardless of actual dropped location.
It could be done but basically itd just add quite a few more events