a version that remember all widget

hw3.py

__author__ = 'tim'
import Tkinter

root = Tkinter.Tk()
screen = Tkinter.Label(root)
screen.pack()

buttons = Tkinter.Frame(root)
buttons.pack()

class Command:
    def __init__(self, screen,  button):
        self.button = button
        self.screen = screen
    def action(self):
        self.screen['text'] = self.button['text']

for i in range(10):
    button = Tkinter.Button(buttons, text=str(i))

    trigger = Command(screen, button)

    button.config(command=trigger.action)
    button.grid(row=(i/3), column=(i%3))

root.mainloop()