after-resize

Called after a given snip is resized (and after the display is refreshed; use on-resize and begin-edit-sequence to avoid extra refreshes when after-resize modifies the buffer), or after an unsuccessful resize attempt was made

• (send a-wx:media-pasteboard after-resize snip w h resized?) -> void
      snip : wx:snip% object
      w : inexact real
      h : inexact real
      resized? : boolean

  If resized? is not #f, the snip was successfully resized.