Thanks Peter, but while we are on the topic of the Chord Builder.
Please allow the customer to change the root chord/key in the tool.
Currently, you have to exit the tool and change the key to the song to get the tool to change, if you're interested in experimenting with other keys.
Also, in the next major release consider adding a few more options like Relative Roman Numeral I, ii, borrowed chord IV/V, transition chords, common progressions and maybe a hard link to a quick video on harmonizing, common next chords ext.
hooktheory.com does a great job of making music theory simple to understand.
Thanks