[Evolution] Regenerate vfolders?

[Adam Kessel <adam rosi-kessel org>]

This seems like it ought to be an FAQ, but apparently it isn't:

Is there anyway to force regeneration of a vFolder? For example,
messages remain in the "unread messages" vFolder until Evolution is shut
down and restarted, even if they become "read."  I've searched for some
way to update the contents short of changing the vFolder rules, but
can't find any such method.
-- 
Adam Kessel
http://adam.rosi-kessel.org