DragHandler makes its target jump if you start dragging in the margin area

See attached. The DragHandler has margin:20. Place the mouse inside the cyan line but outside dark square: that is inside the margin around the DragHandler. Press, and start dragging. When the drag threshold is exceeded, the target will jump to a position such that it's centered under the mouse cursor. This is very different from when you drag inside the dark square: it will retain its position relative to the mouse cursor as you drag around.