/// allows loading extra data into data sets (for importing etc.)
virtual void load_extra_data (ARDOUR::SessionMetadata const & /*data*/) { }
/// Saves data to session
virtual void save_data () = 0;
/// allows loading extra data into data sets (for importing etc.)
virtual void load_extra_data (ARDOUR::SessionMetadata const & /*data*/) { }
/// Saves data to session
virtual void save_data () = 0;