Handler will be invoked synchronously, when a new message has been injected into the bus. This function is mostly used internally. Only one sync handler can be attached to a given bus.

If the handler returns GST_BUS_DROP, it should unref the message, else the message should not be unreffed by the sync handler.

alias GstBusSyncHandler = GstBusSyncReply function(GstBus* bus, GstMessage* message, void* userData)

Return Value

GstBusSyncReply stating what to do with the message