void gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func,
gpointer user_data, GDestroyNotify notify);
/* asynchronous message notifications */
void gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func,
gpointer user_data, GDestroyNotify notify);
/* asynchronous message notifications */