void on_size_request (Gtk::Requisition *);
bool on_button_press_event (GdkEventButton *);
bool on_motion_notify_event (GdkEventMotion *);
void on_size_request (Gtk::Requisition *);
bool on_button_press_event (GdkEventButton *);
bool on_motion_notify_event (GdkEventMotion *);