gtk: non-ascii characters in frame title

[Reiner Steib]

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

- Start Emacs: emacs -q -no-site-file

- Create a new frame: C-x 5 2

- Rename the buffer with a name containing a non-ascii character:
  C-x b *ä* RET

=> The Window title is not renamed.  Title remains "*Minibuf-1*".
   On the terminal, I get:

$ emacs -q -no-site-file

(emacs:15041): Gdk-WARNING **: Error converting from UTF-8 to 'ISO-8859-1': 
Invalid byte sequence in conversion input
(emacs:15041): Gdk-WARNING **: Error converting from UTF-8 to 'ISO-8859-1': 
Invalid byte sequence in conversion input 


In GNU Emacs 21.3.50.4 (i686-pc-linux-gnu, GTK+ Version 2.2.1)
 of 2004-08-18 on lumberjack
configured using `configure '--prefix=/import/xtra/emacs/HEAD' '--with-gtk''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: POSIX
  value of $LC_CTYPE: en_US.ISO_8859-1
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: POSIX
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t

Major mode: Fundamental

Minor modes in effect:
  mouse-wheel-mode: t
  menu-bar-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t

Recent input:
<help-echo> <help-echo> <help-echo> C-x 5 2 <switch-frame> 
C-x b * ä * <return> M-x r e p o <tab> s <tab> <home> 
<right> <right> <right> <right> C-k r <tab> <retur
n>

Recent messages:
Loading mwheel...done
(emacs -q -no-site-file)
Loading disp-table...done
Loading tooltip...done
Loading image...done
Making completion list...
Loading help-mode...done
Loading emacsbug...done