Subclasses should override this method to get notified of the drag events in a drag sequence.
This method is called in the middle of a drag sequence, between the OnStartDrag and the OnEndDrag methods.
Unlike the OnMouseDrag method, this method will not get called until after the MinDragStartDistance has been reached.
Notes to Inheritors: Overriding methods must still call base.OnDrag()
for correct behavior.
PDragSequenceEventHandler Class | UMD.HCIL.Piccolo.Event Namespace