'Return a box with OK and cancel buttons.'

def create_button_box(self):

    button_box = Gtk.Box(spacing=6)
    OK_button = Gtk.Button.new_with_label('OK')
    OK_button.connect('clicked', self.on_click_ok)
    cancel_button = Gtk.Button.new_with_label('Cancel')
    cancel_button.connect('clicked', self.on_click_cancel)
    button_box.pack_start(OK_button, False, False, 10)
    button_box.pack_end(cancel_button, False, False, 10)
    return button_box
