rem: g_return_val_if_fail (gtx != NULL, 0); g_return_val_if_fail (GTK_IS_XINE (gtx), 0); g_return_val_if_fail (gtx->priv->xine != NULL, 0);
add: g_return_if_fail (gtx != NULL); g_return_if_fail (GTK_IS_XINE (gtx)); g_return_if_fail (gtx->priv->xine != NULL);
context: gtk_xine_dvd_event (GtkXine *gtx, GtkXineDVDEvent type){        xine_event_t event;	g_return_val_if_fail (gtx != NULL, 0);	g_return_val_if_fail (GTK_IS_XINE (gtx), 0);	g_return_val_if_fail (gtx->priv->xine != NULL, 0);        switch (type)        {        case GTX_DVD_ROOT_MENU:                event.type = XINE_EVENT_INPUT_MENU1;                break;        case GTX_DVD_TITLE_MENU:                event.type = XINE_EVENT_INPUT_MENU2;                break;        case GTX_DVD_SUBPICTURE_MENU:                event.type = XINE_EVENT_INPUT_MENU4;                break;        case GTX_DVD_AUDIO_MENU:                event.type = XINE_EVENT_INPUT_MENU5;                break;        case GTX_DVD_ANGLE_MENU:                event.type = XINE_EVENT_INPUT_MENU6;                break;        case GTX_DVD_CHAPTER_MENU:                event.type = XINE_EVENT_INPUT_MENU7;                break;        case GTX_DVD_NEXT_CHAPTER:                dvd_skip_behaviour (gtx, 1);                event.type = XINE_EVENT_INPUT_NEXT;                break;        case GTX_DVD_PREV_CHAPTER:                dvd_skip_behaviour (gtx, 1);                event.type = XINE_EVENT_INPUT_PREVIOUS;                break;        case GTX_DVD_NEXT_TITLE:                dvd_skip_behaviour (gtx, 2);                event.type = XINE_EVENT_INPUT_NEXT;                break;        case GTX_DVD_PREV_TITLE:                dvd_skip_behaviour (gtx, 2);                event.type = XINE_EVENT_INPUT_PREVIOUS;                break;        case GTX_DVD_NEXT_ANGLE:                event.type = XINE_EVENT_INPUT_ANGLE_NEXT;                break;        case GTX_DVD_PREV_ANGLE:                event.type = XINE_EVENT_INPUT_ANGLE_PREVIOUS;                break;        default:                return;        }        event.stream = gtx->priv->stream;        event.data = NULL;        event.data_length = 0;        xine_event_send (gtx->priv->stream,                        (xine_event_t *) (&event));}