These are not static methods. These are invoked on objects.

Getters can be made const, i.e. 'int get_width()' const.
  -You're not modifying the object at all so tell the consumer.

The return value can also be made const, i.e. 'const int get_width() const'.
  -If you don't make the return value const you can do silly things like 'window.get_width()=1'