Latest update (and likely one to be used at event) modifed the 5x4 version.
The "code_MidiQT_bankSwitch.py" version drops back to 16 midi buttons, with the 5th (default address) board being used as a "bank switch" - it changes the midi notes associated with the midi buttons. 4 arrays are used to hold the Banks, and pressing one of the BankSwitches, changes which bank is active.
This is the arcadeQT with the colored buttons. The leds in these are Digital IO and stay on to show which bank is active.