rafael@debian:~/glade$ ./xmlgenava 

(xmlgenava:7019): GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT (object)' failed

(xmlgenava:7019): GLib-GObject-WARNING **: instance of invalid non-instantiatable type `(null)'

(xmlgenava:7019): GLib-GObject-CRITICAL **: g_signal_emit_valist: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

(xmlgenava:7019): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed

(xmlgenava:7019): GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT (object)' failed

(xmlgenava:7019): GLib-GObject-WARNING **: instance of invalid non-instantiatable type `(null)'

...

This messages are generated when I click the application, after insert the text with:

  textBuffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (lookup_widget (GTK_WIDGET (button), "textviewXMLInformation")));
  gtk_text_buffer_get_start_iter (textBuffer, textIter);
  gtk_text_buffer_insert (textBuffer, textIter, " Documento XML generado con éxito.", -1);