# File gtk/sample/misc/cairo-pong.rb, line 132
    def initialize(margin=0.05)
      @margin = margin
      
      @left_paddle = Paddle.new(self, @margin, 0.5)
      @right_paddle = Paddle.new(self, 1 - @margin, 0.7)
      @paddles = [@left_paddle, @right_paddle]
      @ball = Ball.new
    end