tkinter checkbutton rendering problem

[RMaple]

Hello,
    I have something strange going on with a tkinter checkbutton. It is 
created using

Checkbutton(self, bitmap="@small_light.xbm",indicatoron=0)

In my .Xdefaults file, I have the following two items.

tk*background:                  gray80
tk*activebackground:            gray90

When the button is selected but inactive, the shadow borders of the the 
sunken representation are drawn in shades of pink!  When active (cursor 
over the button) the button is drawn correctly.  The unselected (raised) 
rendering is also drawn correctly.  Finally, if I don't set the 
activebackground color, the button is always drawn correctly. 
(Unfortunately, the default is black, which I just don't like.  Is this 
some strange colormap problem or a problem with tkinter?

I am running under Mandrake linux (8.1), python 2.1.1, truecolor X 
display.

Thanks,
Ray Maple