previewed Edge
While a drag is in flight, the edge of the dock zone currently under the pill — the pill previews this edge's orientation live, flipping horizontal↔vertical as the drag crosses zone boundaries. null while not dragging.
While a drag is in flight, the edge of the dock zone currently under the pill — the pill previews this edge's orientation live, flipping horizontal↔vertical as the drag crosses zone boundaries. null while not dragging.