workstation stalls when mouse-2 is clicked on menu-bar

[Klaus Zeitler]

Symptoms:

I accidently hit mouse button 2 when I tried to open a menu and that was it.
My workstation stalled. A strange icon appeared, I'd say it looks like a 
folder with 2 pages, but I always have difficulties to recognize icons.
No keyboard input was possible, and I had to kill emacs from another
workstation. 
Tried it a 2nd time to see if it's reproducibole and yes the same thing
happened again.

In GNU Emacs 22.0.50.30 (sparc-sun-solaris2.8, Motif Version 2.1.0)
 of 2005-07-12 on sfsws4
X server distributor `Sun Microsystems, Inc.', version 11.0.6410
configured using `configure '--with-gcc' 
'--prefix=/vol/freeware/SunOS-5.8/emacs/cvs' 
'--sharedstatedir=/vol/freeware/SunOS-5.8/emacs/cvs/share' 
'--with-x-toolkit=motif' 
'--x-includes=/usr/openwin/include:/usr/local/gnu/include:/opt/exp/gnu/include:/opt/exp/include:/opt/exp/lib/xpm/include'
 
'--x-libraries=/usr/openwin/lib:/usr/local/gnu/lib:/opt/exp/gnu/lib:/opt/exp/lib:/opt/exp/lib/xpm/lib'
 '--with-pop' 'CC=gcc''

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
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
  tool-bar-mode: t
  mouse-wheel-mode: t
  auto-compression-mode: t
  menu-bar-mode: t
  blink-cursor-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t
  next-error-follow-minor-mode:  Fol

Recent input:
<help-echo> <help-echo> <help-echo> <menu-bar> <help-menu> 
<report-emacs-bug>

Recent messages:
Loading mwheel...done
(/usr/local/gnu/cvs/head/bin/emacs -Q --no-site-file)
Loading tool-bar...done
Loading image...done
For information about the GNU Project and its goals, type C-h C-p.
Loading emacsbug...done