Since this is my first Tk prog I haven't done too much converting. I think the fact that I want to do more work on the GUI is one of the driving my feeling that I want the program in an OO form before I go forward...:-)?

I haven't gotten to the point of doing anything complicated in Tk. No objects based in Tk (yet). Right now I'm leaning toward abstracting the Tk-specific parts, toward eventually allowing other windowing systems.
L