Tkinter (and IDLE) window "docking?" effect when dragging root window to edge of display

[python at bdurham.com]

Python 2.6/2.7 (32-bit) for Windows: When I drag a Tkinter root
window to the left, upper, or right edge of my display ... as
soon as my mouse cursor hits the visible edge of the display ...
as if I'm trying to dock the window on the edge in question ... a
giant phantom Tkinter window pops up underneath my window showing
the size and placement of my root window if I would release my
mouse button.

You can see the identical behavior if you drag a non-maxmized
IDLE window to one of your screen edges (left, top, bottom). This
behavior seems to be "by design".

I'm looking for a way to either disable this "docking"
functionality or trap the "docking" event and size and position
my root window according to custom needs. I've been googling this
question and I can't seem to find the right terms to describe the
event that is being raised or the behavior that I'm observing.

Any ideas?
Malcolm
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