class PyApp(gtk.Window):
    def __init__(self):
        # Added scaffolding to get it to actually run
        super(PyApp, self).__init__()

        self.set_title("Toolbar")
        self.set_size_request(250, 200)
        self.modify_bg(gtk.STATE_NORMAL, gtk.gdk.Color(6400, 6400, 6440))
        self.set_position(gtk.WIN_POS_CENTER)

        # Start of edited code
        vBox = gtk.VBox(False, 0)
        vBox.set_size_request(400,500)
        vBox.set_border_width(2)
        self.add(vBox)

        bar = gtk.Toolbar()
        bar.set_style(gtk.TOOLBAR_ICONS)
        closeButt = gtk.ToolButton(gtk.STOCK_CLOSE)
        # You can do your original non-stock button instead,
        # but must make it text instead of icons then.
        bar.insert(closeButt,0)
        vBox.pack_start(bar, False, False, 0)
        # End of edited code

        # More scaffolding to make it into a running program
        self.connect("destroy", gtk.main_quit)
        self.show_all()

PyApp()
gtk.main()