Hi there
I think to remember that somebody said this option is awful, but I think it’s actually amazing
Send chords to the Fretboard area, using one of your hands or Scaler
Then use a filter (MIDI Polysher, etc.) to stop unwanted buttons in the top part of the Key Switches area, and use the other hand to play wonderful arpeggios and riffs in the low part of the Key Switches area
AAS Strum-GS 2 has a similar feature called Guitar, but the UJAM one is an improved version
i believe it was the Silk2 instrument which seems backwards.
And why?
The Instrument tool I am speaking about is there (not in the 1st version) and I love it
because you cannot hold a note and switch the pattern 
for a guitarist this is backwards…
I am just trying to do it now, and I still don’t get the point
If I hit a couple of notes in the fretboard area to make a chord, I can hit all notes in the Key Switches area… 
Well, maybe I found what you were speaking about @fossile
The buttons under the red line are toggle buttons, so if you click them to activate, you have to click them a second time to deactivate
All the other buttons instead are not toggle buttons, so you can hit them freely while holding a note in the Key Switches area
