Cannot start GTK apps - gdk_visual_decompose_mask

[David Saxton <david bluehaze org>]

Hello,

Recently (perhaps due to an upgrade to the system, or similar - I'm unsure 
when exactly it happened) gtk apps stopped working (the apps don't display 
any gui - just sit there taking up 100% cpu).

This happens with all gtk apps tested - e.g. gimp, inkscape, gnumeric.

Compiling gtk with debugging support shows the same backtrace:

#0  gdk_visual_decompose_mask (mask=0, shift=0x89d46c, prec=0x89d470) at 
gdkvisual-x11.c:611
#1  0x00002aaaab72c6c8 in _gdk_visual_init (screen=0x89b6c0) at 
gdkvisual-x11.c:194
#2  0x00002aaaab72a81f in _gdk_x11_screen_new (display=0x899cc0, 
screen_number=0) at gdkscreen-x11.c:429
#3  0x00002aaaab714511 in IA__gdk_display_open (display_name=0x0) at 
gdkdisplay-x11.c:183
#4  0x00002aaaab6f8c6a in IA__gdk_display_open_default_libgtk_only () at 
gdk.c:272
#5  0x00002aaaab3ec63b in IA__gtk_init_check (argc=0x0, argv=0x89d46c) at 
gtkmain.c:702

It seems like they are stuck in the following while loop in gdkvisual-x11.c 
(as shown by the backtrace):

 while (!(mask & 0x1))
    {
      (*shift)++;
      mask >>= 1;
    }

However, I don't know enough about gtk to investigate any further - so perhaps 
someone has suggestions on what is going wrong / how to fix this?

Thanks,
David Saxton