- ;; Note: in Emacs 22 and older, return of nil meant the file was
- ;; unregistered. This is potentially a source of
- ;; backward-compatibility bugs.
+ ;; Note: we usually return nil here for unregistered files anyway
+ ;; when called with only one argument. This doesn't seem to cause
+ ;; any problems. But if we wanted to change that, we should
+ ;; probably opt for redefining the `registered' command to return
+ ;; non-nil even for unregistered files (maybe also rename it), and
+ ;; then make sure that all `state' implementations handle
+ ;; unregistered file appropriately.