def METHOD_NAME(self, msg):
    import gtk
    window = gtk.Dialog(title="Error")
    window.connect("destroy", self.closeErrorWindow)
    window.set_modal(True)
    text = gtk.Label(msg)
    button = gtk.Button(stock=gtk.STOCK_CLOSE)
    button.connect("clicked", self.closeErrorWindow)
    window.vbox.add(text)
    window.vbox.add(button)
    window.show_all()