And similar code for topics:

From: Dick Knowles <knowles@averstar.com>
Subject: Re: gnus-easy-threading.el
Newsgroups: gnu.emacs.sources
Date: Fri Mar 31 14:06:13 2000 -0500
Organization: Intermetrics, Inc.

Taking my lead from Ingo's threading code, I made some for topic mode:

(defun my-gnus-topic-show-topic ()
  "Show the hidden topic."
  (interactive)
  (if (gnus-group-topic-p)
      (gnus-topic-show-topic)
    (gnus-topic-read-group)))

(add-hook 
 'gnus-started-hook
 '(lambda ()
    (define-key gnus-topic-mode-map [(right)] 'my-gnus-topic-show-topic)
    (define-key gnus-topic-mode-map [(left)]  'gnus-topic-hide-topic)
    ))

-- 
Arcady Genkin                                 http://www.thpoon.com
Nostalgia isn't what it used to be.