on-move-to (augmentable only) in pasteboard%

Called before a snip is moved in the editor, after can-move-to? is called to verify that the move is allowed. The after-move-to method is guaranteed to be called after the move has completed.

The editor is internally locked for writing when this method is called (see also Locks). Use after-move-to to modify the editor, if necessary. See also on-interactive-move and interactive-adjust-move.

• (send a-pasteboard on-move-to snip x y dragging?) -> void
     snip : snip% object
     x : real number
     y : real number
     dragging? : boolean

  If dragging? is not #f, then this move is a temporary move for dragging.