Crash in gtkutil.c

[Chong Yidong]

I got a crash in gtkutil.c while playing around with msb.el.  I'll try
to see if I can produce a recipe, but here is the backtrace; hopefully
it is enough:

(gdb) bt full
#0  0xb7e17031 in gtk_widget_show () from /usr/lib/libgtk-x11-2.0.so.0
No symbol table info available.
#1  0xb7d3a3a5 in gtk_menu_item_new_with_label ()
   from /usr/lib/libgtk-x11-2.0.so.0
No symbol table info available.
#2  0x080ee837 in create_menus (data=Variable "data" is not available.
) at gtkutil.c:2067
        utf8_label = 0x0
        item = (widget_value *) 0x8852600
        wmenu = (GtkWidget *) 0x8752e28
        group = (GSList *) 0x0
#3  0x080eed96 in xg_create_widget (type=0x81a32c8 "popup", 
    name=0x81a32c3 "menu", f=0x86c03a0, val=0x85925b0, 
    select_cb=0x808be80 <popup_selection_callback>, 
    deactivate_cb=0x808aaf0 <popup_deactivate_callback>, 
    highlight_cb=0x808ab00 <menu_highlight_callback>) at gtkutil.c:2152
        w = Variable "w" is not available.
(gdb) f 2
#2  0x080ee837 in create_menus at gtkutil.c:2067
2067              w = gtk_menu_item_new_with_label (utf8_label);
(gdb) p utf8_label
$3 = 0x0
(gdb) p item->name
$4 = 0x884eccc "\220&\212\b:load-toplevel"
(gdb) p data
Variable "data" is not available.
(gdb) p item->lname
$5 = 0
(gdb) p item-> enabled
$6 = 1
(gdb) p item-> selected
$7 = 0
(gdb) p item->button_type
$8 = BUTTON_TYPE_NONE
(gdb) p item->next
$9 = (struct _widget_value *) 0x8741f88
(gdb) p item->next->name
$10 = 0x8899ffc "Version Control (1)"