rem: static void apply_cb (GtkWidget *widget, gpointer data)
add: static void apply_cb (GtkWidget *widget, gint pagenum, gpointer data)
context: static void apply_cb (GtkWidget *widget, gpointer data){	gnibbles_properties_destroy (properties);	properties = gnibbles_properties_copy (t_properties);	gnibbles_properties_save (properties);}