# Display hello, world in a button; clicking it quits the program

import sys

from Tkinter import *

def main():

    root = Tk()

    button = Button(root)

    button['text'] = 'Hello, world'

    button['command'] = quit_callback       # See below

    button.pack()

    root.mainloop()

def quit_callback():

    sys.exit(0)

main()