after-reorder (augmentable only) in pasteboard%

Called before a snip is moved in the pasteboard's front-to-back snip order (and after the display is refreshed; use on-reorder and begin-edit-sequence to avoid extra refreshes when after-reorder modifies the editor).

See also can-reorder? and on-edit-sequence.

No internals locks are set when this method is called.

• (send a-pasteboard after-reorder snip to-snip before?) -> boolean
     snip : snip% object
     to-snip : snip% object
     before? : boolean

  If before? is #t, then snip was moved before to-snip, otherwise snip was moved after to-snip