-As suggested, I've added bass fretboards. You can now switch between guitar / bass 4 / bass 5 / bass 6. Default is guitar.
-You can now use the stylus on every button (touch a card to display its notes).
-Changed UI to make it a bit less ugly.
It's ugly and it's my first app in C ever, so I guess it could be improved, but it works. The stylus is still buggy (I don't know how I can do the same action just ONCE with "PA_SpriteTouched") so I recommend you use the pad for now.