sigc::signal<void, const std::string &> signal_title_changed;
sigc::signal<void, const Msp::Time::TimeDelta &> signal_duration_changed;
sigc::signal<void, const Msp::Time::TimeDelta &> signal_position_changed;
sigc::signal<void, const std::string &> signal_title_changed;
sigc::signal<void, const Msp::Time::TimeDelta &> signal_duration_changed;
sigc::signal<void, const Msp::Time::TimeDelta &> signal_position_changed;