Transparent window in python w/tkinter

[Matt Singer]

I'm trying to create a GUI application in python with Tkinter.  I want
to application window to be a non-rectagular shape.  (For example, I
might want to do something as simple as rounded corners or a circular
window.)

I've figured out how to create a transparent frame, etc, but these
transparent areas do not refresh the data from the windows below. 
(Think about what xeyes does or what windows media player does with
skins.)

If anyone has any experience doing this in tkinter (or even straight
Tcl/tk), any help would be appreciated.