Rename UI frame counter, extract from function.
Change LCD header text a bit.
Separate switch events into three separate variables: switch on, switch transition to on, switch transition to off.
Simple up/down key repeat for changing values in UI. Needs refactoring -- too much repeated code. And maybe a field-specific increment rate handler, so the frequency field repeat magnitude can accelerate.
Create a struct for UI switch state, refactor switch repeat code.