Re: GTK_WARNING and GTK-CRITICAL

[Skip Montanaro <skip pobox com>]

    Maxime> Gtk-WARNING **: invalid cast from (NULL) pointer to `GtkObject'

This is telling you that the GTK_OBJECT() function/macro was handed a NULL
pointer.  

    Maxime> Gtk-CRITICAL **: file gtksignal.c: line 724 (gtk_signal_connect):
    Maxime> assertion `object != NULL' failed.

Same thing here.  Looks like you're passing a NULL to gtk_signal_connect or
something that calls it.  Try running your application under the control of
a debugger and set a breakpoint in gtk_signal_connect.  (Actually, in 1.3.x
at least, gtk_signal_connect is a macro.  I think you may have to break in
gtk_signal_connect_full.)  Once the debugger regains control, print a
traceback and see where your code is involved.

-- 
Skip Montanaro (skip pobox com)
(847)971-7098