inst->back->special(inst->backhandle, code);
if (inst->back) inst->back->special(inst->backhandle, code);
void special_menuitem(GtkMenuItem *item, gpointer data){    struct gui_data *inst = (struct gui_data *)data;    int code = GPOINTER_TO_INT(gtk_object_get_data(GTK_OBJECT(item),						   "user-data"));    inst->back->special(inst->backhandle, code);}