lib/metro/scene.rb
def window=(window)
      @window = window

      state.window = window
      state.clear

      register_events!
      register_actors!
      register_animations!
      register_after_intervals!

      show
    end
def window=(window)
      @window = window

      state.window = window
      state.clear

      register_events!
      register_actors!
      register_animations!
      register_after_intervals!

      show
    end
Setting the window places the scene within in the specified window. Which
 will cause a number of variables and settings to be set up. The {#show}
 method is called after the window has been set.