void button_press(int, int, unsigned, unsigned);
void pointer_motion(int, int);
void apply_camera();
void render();
Marklin::Track3D *pick_track(int, int);
void button_press(int, int, unsigned, unsigned);
void pointer_motion(int, int);
void apply_camera();
void render();
Marklin::Track3D *pick_track(int, int);