Crypto alpha

Here's a screenshot of the mono-alphabetic crypto-tool that I wrote.  The example you see is the puzzle and solution to the first entry in Elonka Dunin's Secret Code and Cryptograms book.  The 'Fill' button fills in all of the substitution values with the '@' symbol.  This is used for reference when decrypting so you can see what letters are missing.  The % column shows the frequency analysis on the contents of the base text (updated when the analyze button is hit.)  The decrypt button takes the Base Text and substitutions each alphabetically character with the substitution from above.

Looking at the resulting Alphabetic Subtitution table, it doesn't appear that this key follow the Affine Cipher which I was half-expecting.  There is somewhat of a pattern, but overall it looks random.