How sentient! Twenty years ago, I wrote a version of this program in C++ for 3.1. The executable failed to load in XP. The source was backed up on floppy (long since discarded). I do remember solving the analogous problem in an analogous way.

It recently occurred to me that modern hardware could probably compensate for the overhead of Tk and perl. I was right. My current version achieves slightly better performance than I remember from the ancient past.