You don't want to override these methods directly in your field
editor because you might require different behavior for each field
in your app and the same field editor is used for all of them. But
remember that the text field that is being edited is the field
editor's delegate. So you can implement the delegate method -
textView:doCommandBySelector: in your text field and do the work
there instead.
I have just one thing to add: instead of subclassing NSTextField and
overriding textView:doCommandBySelector:, it may be easier to just
supply a delegate to the text field and implement the text field
delegate method
