can-delete? (augmentable only) in text%

Called before a range is deleted from the editor. If the return value is #f, then the delete will be aborted.

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-delete, after-delete, and on-edit-sequence.

• (send a-text can-delete? start len) -> boolean
     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).