sigc::signal<void, unsigned> signal_speed_changed;
sigc::signal<void, bool> signal_reverse_changed;
sigc::signal<void, unsigned, bool> signal_function_changed;
sigc::signal<void, unsigned> signal_speed_changed;
sigc::signal<void, bool> signal_reverse_changed;
sigc::signal<void, unsigned, bool> signal_function_changed;