sigc::signal<void, int, int, unsigned, unsigned> signal_button_press;
sigc::signal<void, int, int, unsigned, unsigned> signal_button_release;
sigc::signal<void, int, int> signal_pointer_motion;
sigc::signal<void, int, int, unsigned, unsigned> signal_button_press;
sigc::signal<void, int, int, unsigned, unsigned> signal_button_release;
sigc::signal<void, int, int> signal_pointer_motion;