can-move-to?

Called before a snip is moved in the editor. If the return value is #f, then the move will be aborted.

See also on-move-to and after-move-to.

The editor is internally locked for writing when this method is called (see also Locks).

• (send a-pasteboard can-move-to? snip x y dragging?) -> boolean
      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.