gtk-label-attributes -> GLib-GObject-CRITICAL

[crategus]

cl-cffi-gtk version: 0.0.0
cl-cffi-gtk build date: 0:50 4/9/2012
GTK+ version: 2.24.6
GLIB version: 2.30.0
Machine type: X86
Machine version: Intel(R) Pentium(R) M processor 1.73GHz
Software type: Linux
Software version: 3.0.0-17-generic
Lisp implementation type: SBCL
Lisp implementation version: 1.0.53

This is the example which gives the error message:

(defvar label (make-instance 'gtk-label))
LABEL
(gtk-label-attributes label)
(GTK Program:20881): GLib-GObject-CRITICAL **: g_boxed_copy: assertion `src_boxed != NULL' failed

<PANGO:PANGO-ATTR-LIST {D86AAE1}>