Thread hiding and gnus-summary-line-format

[Lancelot appearing sideways]

Hi.  I use thread-hiding a lot, and I was just thinking today that it
would be nice if the ellipses indicating a hidden thread could be
followed by the number of hidden articles.  I came across "%t" in the
gnus-summary-line-format which will display the count, but I only
want the count to appear when the thread is collapsed; in other
words, I want the %t count to appear and disappear along with the
ellipses.

It looks like what I want can be handled via "%u", but I have no idea
how to write a function like this, knowing very little about Lisp or
Emacs Lisp (though I'm competent in a number of other languages and
don't mind learning).  Could someone cobble together a quick function
that does what I'm looking for, or direct me to a sample
gnus-user-format-function from which I could work?  (In particular, I
wonder how said function would know whether the thread under the
cursor was collapsed or not.)

Thanks!

/
:@-) Scott
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