message types to take into account
Return: the next #GstMessage matching @type that is on the bus, or %NULL if the bus is empty or there is no message matching @type. The message is taken from the bus and needs to be unreffed with gst_message_unref() after usage.
MT safe.
Get a message matching @type from the bus. Will discard all messages on the bus that do not match @type and that have been posted before the first message that does match @type. If there is no message matching @type on the bus, all messages will be discarded. It is not possible to use message enums beyond #GST_MESSAGE_EXTENDED in the @events mask.