How can I best center a Tkinter window on my display screen?

Not knowing Tkinter that well, here is a somewhat simple minded approach:
[php]from Tkinter import *

def center_window(w=300, h=200):
# get screen width and height
ws = root.winfo_screenwidth()
hs = root.winfo_screenheight()
# calculate position x, y
x = (ws/2) - (w/2)
y = (hs/2) - (h/2)
root.geometry('%dx%d+%d+%d' % (w, h, x, y))

root = Tk()
center_window(500, 300)
root.mainloop()
[/php]