Simple Tkinter app works in Linux, not in Windows

[john.orlando at gmail.com]

Hello,
I'm a newbie to Python (literally, within the last two weeks), and I am
playing around with Tkinter to build some simple GUIs.  I am attempting
to build a simple class that displays a GIF.  Here is the code:

#start of code
from Tkinter import *

class DisplayPict(Frame):

    def __init__(self,parent=None):
        Frame.__init__(self,parent)
        self.pack()
        self.img=PhotoImage(file="moon.gif")
        self.can=Canvas(self)
        self.can.create_image(2,2,image=self.img,anchor=NW)
        self.can.pack(fill=BOTH)

        #keep a reference to the img around
        self.can.photo=self.img

if __name__ == '__main__': DisplayPict().mainloop()
#end of code

Anyway, I started with this code in Windoze using IDLE, and everytime I
ran it I kept getting an empty frame (well, presumably with a Canvas
that had nothing in it).  I kept thinking that it had to be something
to do with the whole images-get-garbage-collected-if-not-referenced
issue that I read so much about.  So I tried a bunch of different
permutations and nothing made a difference.

On a whim, I tried this code under Linux, and amazingly, it worked just
fine: the image was displayed as expected.

So...I am confused.  I tried to do my homework (i.e., read through
"Programming Python", "Learning Python", and scouring the internet),
but I can't come up with an explanation as to why this doesn't work
under Windoze.  Can anyone out there show me the error in what I have?

Thanks in advance,
John O