# File lib/json/editor.rb, line 230
      def add_item(label, keyval = nil, klass = MenuItem, &callback)
        label = "#{label} (C-#{keyval.chr})" if keyval
        item = klass.new(label)
        item.signal_connect(:activate, &callback)
        if keyval
          self.signal_connect('key-press-event''key-press-event') do |item, event|
            if event.state & Gdk::Window::ModifierType::CONTROL_MASK != 0 and
              event.keyval == keyval
              callback.call item
            end
          end
        end
        menu.append item
        item
      end