Catching up topics

[Paul Stevenson <spaul@mail.phy.ornl.gov>]

In pgnus 0.91 I can catch up all the groups in a topic by hitting # c y
(or c y since I have rebound 'c' to work on topic lines, but one must
normally hit # first). 

This is well, but if the topic is hidden, like my sent-mail topic often
is, and I try and do the same, then although the groups are caught-up,
the topic lines are not updated.  I tried to look into fixing this, but
got confused.  I note that the function
gnus-topic-update-topics-containing-group contains the comment

	;; This is probably not entirely correct.  If a topic
	;; isn't shown, then it's not updated.  But the updating
	;; should be performed in any case, since the topic's
	;; parent should be updated.  Pfft.

which might be relevant. I'm not sure what Pfft means, though :-)