#!/usr/bin/env python

import gtk

class MyButton(gtk.Button):
    def __init__(self, label=None):
        # chain up to parent __init__
        gtk.Button.__init__(self, label)

    def set_label(self, label):
        gtk.Button.set_label(self, label + " dork!")

def buttonPressed(button):
    button.set_label("I've been pressed!")

win = gtk.Window()
button = MyButton('Hello, world. Press me')
win.add(button)
button.connect('pressed', buttonPressed)
win.show_all()
win.connect('destroy', lambda w: gtk.main_quit())

gtk.main()