# File gtk/sample/gtk-demo/cairo-operator.rb, line 25
    def initialize
      super('cairo operator')
      @operator = Cairo::OPERATOR_ADD

      set_default_size(400, 400)
      
      @drawing_area = child
      remove(@drawing_area)
      
      vbox = Gtk::VBox.new
      vbox.pack_start(@drawing_area, true, true)
      vbox.pack_start(operator_selector, false, false)
      add(vbox)
    end