Learning Tkinter

[Doran, Harold]

I am currently reading An Intro to Tkinter (1999) by F. Lundh. This doc
was published in 1999 and I wonder if there is a more recent version.
I've googled a bit and this version is the one I keep finding. I like
how this document is organized and also how it provides the code with
visuals of what should appear on the screen. If there are other docs I
should read, please let me know.

Second, I am trying to work through a couple of the examples and make
some small tweaks as I go to see how new things can work. In the first
case, I have copied the code in the book to see how the menu works and
are created as in the example menu.py below. I see how menus are created
and how the command option is used to call the function callback.

# menu.py
from Tkinter import *

def callback():
    print "called the callback!"

root = Tk()

# create a menu
menu = Menu(root)
root.config(menu=menu)

filemenu = Menu(menu)
menu.add_cascade(label="File", menu=filemenu)
filemenu.add_command(label="New", command=harold)
filemenu.add_command(label="Open...", command=callback)
filemenu.add_separator()
filemenu.add_command(label="Exit", command=callback)

helpmenu = Menu(menu)
menu.add_cascade(label="Help", menu=helpmenu)
helpmenu.add_command(label="About...", command=callback)

mainloop()

However, I now want to incorporate a basic python program with a
command. Say I have a simple program called test.py 

# test.py
filename = raw_input("Please enter the file you want to open: ")
new_file = raw_input("Save the output file as: ")

f = open(new_file, 'w')
new = open(filename, 'r')

for line in new:
	x = line.split('\t')
	print >> f, x[0],':', x[1]     
f.close()

To make this example complete assume I have a text file like this

# data.txt
1	one
2	two
3	three
4	four

So, the user currently just follows directions on the screen, enters the
file names, and I get what I want. I'd like to try experimenting with
gui programming to see if the python programs I have written can be made
even more user friendly. I currently use py2exe to create executables so
that others in my organization can use these programs. 
 
In that spirit, say I want to have a menu option that allows the user to
search their computer for this file, execute the python code and then
save the result as a user-defined filename. So, I guess my questions are
how do I associate the portion of code in menu.py
"filemenu.add_command(label="Open...", command=callback)" with an
operation that gives the user the ability to search the drives on their
machine and then once they do let python execute the code in test.py?

Many thanks,