From: Koen Danckaert on
Larry,

I don't know if you remember, but you once asked a similar question, and one of the ideas that came out was to add a trace to the radiobutton variable, in which you can then modify the colors of the buttons depending on which one is selected.

http://groups.google.com/group/comp.lang.tcl/browse_thread/thread/9c3d7acc68d95f9a/6864fb9ba7bf9f96#6864fb9ba7bf9f96

Koen