Is it possible to implement notmuch_threads_back and notmuch_messages_back?
And I guess will make sense to have also notmuch_tags_back.

This functions will do the oposite than notmuch_threads_advance and
notmuch_messages_advance. So I can use them as iterators going back and forward.

I didn't check the implementation of notmuch. I don't know if will be easy or
will need to redesign a lot of code.

-- 
Rubén Pollán  | jabber:meskio@jabber.org
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   La felicidad no es hacer lo que deseas
         es desear lo que haces.