Someone

    itemOpen.signal_connect("activate"){
      #dialog for choosing a file, however no opening is implemented
      openFileDialog = Gtk::FileChooserDialog.new("Open File",
                                     nil,
                                     Gtk::FileChooser::ACTION_OPEN,
                                     nil,
                                     [Gtk::Stock::CANCEL, Gtk::FileChooserDialog::RESPONSE_CANCEL],
                                     [Gtk::Stock::OPEN, Gtk::FileChooserDialog::RESPONSE_ACCEPT])
                                     
    if openFileDialog.run == Gtk::FileChooserDialog::RESPONSE_ACCEPT
      #puts "filename = #{openFileDialog.filename}"
      @xmlfilename=openFileDialog.filename;
      puts @xmlfilename
    end
      openFileDialog.destroy
      
      xr = XmlReader.new
      xr.go(@xmlfilename)
      xr.showAutomatons
    }