bug#4329: 23.1.50; Emacs 23.1.50 hides the menu bar when Gnus is started

When I start Gnus (with M-x gnus) on CVS Emacs on Solaris 11, when
loading is almost finished, the menu bar is hidden and I have no way to
recover it.  This makes CVS Emacs completely (well, more or less) unusable.
This is a regression from Emacs 23.1.

In GNU Emacs 23.1.50.1 (sparc-sun-solaris2.10, GTK+ Version 2.12.9)
 of 2009-08-31 on padouk
Windowing system distributor `Sun Microsystems, Inc.', version 11.0.6620
configured using `configure  'CC=cc' 'CXX=CC' 'CPPFLAGS=-I/vol/graphics/include' 'LDFLAGS=-L/vol/graphics/lib -R/vol/graphics/lib' '--prefix=/vol/gnu' '--infodir=/vol/gnu/info' '--mandir=/vol/gnu/man' '--libexecdir=/vol/gnu/lib' '--localstatedir=/vol/gnu/share/emacs/var' '--with-x-toolkit=gtk''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: en_US.ISO8859-15@euro
  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: iso-latin-9-unix
  default-enable-multibyte-characters: t

Major mode: Group

Minor modes in effect:
  gnus-undo-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-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:
<return> C-h a b u g <return> C-x o C-v C-x 0 <escape> 
x r e p o r C-g C-x b <return> C-x b <return> <escape> 
x r e p o <tab> r t <tab> <return>

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Load-path shadows:
/vol/gnu/share/emacs/site-lisp/psgml-other hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-other
/vol/gnu/share/emacs/site-lisp/psgml-api hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-api
/vol/gnu/share/emacs/site-lisp/psgml-charent hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-charent
/vol/gnu/share/emacs/site-lisp/psgml-info hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-info
/vol/gnu/share/emacs/site-lisp/psgml-dtd hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-dtd
/vol/gnu/share/emacs/site-lisp/psgml-edit hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-edit
/vol/gnu/share/emacs/site-lisp/psgml-parse hides /vol/gnu/share/emacs/site-lisp/psgml/psgml-parse
/vol/gnu/share/emacs/site-lisp/psgml hides /vol/gnu/share/emacs/site-lisp/psgml/psgml
/vol/gnu/share/emacs/site-lisp/info-look hides /vol/gnu/share/emacs/23.1.50/lisp/info-look