from Tkinter import *
from threading import *

window = Tk()
canvas = Canvas(window, width = 400, height = 300)
canvas.pack()
x0 = 10
y0 = 50
x1 = 60
y1 = 100
i = 0
deltax = 2
deltay = 3
which = canvas.create_oval(x0,y0,x1,y1,
                           fill="red",
                           tag='redBall')

from time import sleep

def otherthread():
  while 1:
    global x1, x0, y1, y0, deltax, deltay
    if x1 >= 400:
        deltax = -2
    if x0 < 0:
        deltax = 2
    if y1 > 300:
        deltay = -3
    if y0 < 0:
        deltay = 3
    x0 += deltax
    x1 += deltax
    y0 += deltay
    y1 += deltay
    sleep(0.02)


t = Thread(None, otherthread)
t.start()

while True:
    canvas.move('redBall', deltax, deltay)
    canvas.after(20)
    canvas.update()
window.mainloop()