[Tutor] Tkinter question

[Chris Scott]

I'm going through (well, was going through 'til I stalled) the Tkinter
introduction and am wondering what I'm doing wrong regarding keyboard input.
I took the mouse-button binding example and thought to adapt it (very
simply) to a keyboard event. I'm just not understanding this... here's the
program as I've changed it:

# file bind1.py

from Tkinter import *

root = Tk()
def testPrint(event):
    print "pressed key"
    
frame = Frame(root, width=200, height=200)
frame.bind("<Return>", testPrint)
frame.pack()

root.mainloop()

It's pretty much the same as the one printed, except I've swapped the
<Button-1> reference for a <Return> reference (have tried with and without
<>) but I don't get any output in the window when I press the return key. It
worked with the mouse button. Am I just typing it in wrong? The
documentation isn't very helpful to me. I appreciate any help, thanks.

- Chris