in reply to Tk cryptogram (no, not cryptography)

I'm still learning Tk myself, so I can't really comment on much there - just one thing to add because I think it's a nice Perl feature. =)

You can create the @letters array with the following line:
my @letters = (a..z);

It's able to increment the letters up from a to z. I just think it's an interesting feature that people can play with. =)