bug#2282: 23.0.90; rmail -- rmail-summary splits frame into three parts...

When one does a M-x rmail, and then invokes rmail-summary, the frame
is split into three parts:

+-----------+----------+
|           |          |
| *scratch* |  rmail   |
|           |          |
+-----------+----------+
|   rmail-summary      |
|                      |
+----------------------+


In GNU Emacs 23.0.90.1 (i686-pc-linux-gnu, GTK+ Version 2.12.11)
 of 2009-02-11 on beryx
Windowing system distributor `The X.Org Foundation', version 11.0.10402000
configured using `configure  'PATH=/home/ams/l/bin:/usr/local/bin:/usr/bin:/bin:/usr/games' 'PKG_CONFIG_PATH=/home/ams/l/lib/pkgconfig''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: RMAIL Summary

Minor modes in effect:
  tooltip-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
M-x r m a i l <return> y n d d d h M-x r e p o <tab> 
r t <tab> <return>

Recent messages:
Getting mail from the remote server ...
Counting new messages...done (5)
Saving file /home/ams/RMAIL...
Wrote /home/ams/RMAIL
5 new messages read
Added to /home/ams/RMAIL.inbox:sysadmin@kreditor
Added to /home/ams/RMAIL.inbox:ams@kreditor
No following nondeleted message
Computing summary lines...done
Making completion list...