On Thu, 11 Feb 2010 15:20:54 +0100 (CET), racin@free.fr wrote:

> Using a prefix arg to invert search order would conflict with my patch
> http://notmuchmail.org/pipermail/notmuch/2009/000914.html in which the
> prefix arg is used to show deleted messages. I don't known which
> behaviour for prefix patch would be best.

I always understood a prefix arg to invert the original (or provide a
numeric repetition), but I do not have a wide sample to tell if this is
how most elisp implements it. 

> Though we can also add "toggle keys" that toggle search order, or
> toggle display of deleted messages, which would solve the problem.

There is the 'o' key now which toggles the search order, isn't there? 

m