I reviewed too, and already committed you and Levente's changes.

>    yes I like the repeat in atomicUpdatePreferences:.  That's safe.  I don't
> care much for the method temp in refEvent: cuz I think the message keyword
> types anEvent item adequately.  Not sure about storePreferencesIn: not
> taking a copy of preferencesDictionary.  Surely it's safer to take the copy.

I had similar doubts initially, until I read Levente's comment:  He
reminds us that the dictionary is NEVER updated.  Only read and
replaced whole.  A copy there is even misleading to the reader.

> So let me take the change to atomicUpdatePreferences: and get this show on
> the road :-).  Thanks for your review!

Already done.  Thanks Eliot and Levente!