on-delete (augmentable only) in text%

Called before a range is deleted from the editor, after can-delete? is called to verify that the deletion is ok. The after-delete method is guaranteed to be called after the delete has completed.

The editor is internally locked for writing during a call to this method (see also Locks). Use after-delete to modify the editor, if necessary.

See also on-edit-sequence.

• (send a-text on-delete start len) -> void
     start : exact non-negative integer
     len : exact non-negative integer

  The start argument specifies the starting position of the range to delete. The len argument specifies number of items to delete (so start + len is the ending position of the range to delete).