bool on_expose_event (GdkEventExpose*);
bool on_button_press_event (GdkEventButton*);
bool on_button_release_event (GdkEventButton*);
bool on_expose_event (GdkEventExpose*);
bool on_button_press_event (GdkEventButton*);
bool on_button_release_event (GdkEventButton*);