Thanks for your answer, but I some problems: When I edit TextField 1 and then select TextField 2, undo on TextField 1 doesn't work. Undo after some editing sometimes throws an exception or crashes. Selecting a TextField registers an undo. and questions: Where should I implement undo with a Toggle, Picker or List (move, delete)? Is it possible to disable the built-in TextField undo and implement my own?

Annother related question: Why does the programChange struct have one bank member and the MIDI2ProgramChange two bank_msb and bank_lsb parameters?