when I add new note columns by writing in them via the APU, then those new note columns will not be visible until I click on the + in the pattern editor.
Is there any additional function to make those new columns visible or is this just a bug in the API?
Oh, you have to do it explicitly on a selected track! That is strange. Wouldn’t it make more sense to automatically show them when they are added?
I do this in my “Split into separate tracks” tool: Whenever I stumble upon a note I put it into the appropriate track. If at this position there is already a note, then I copy the data to the next free column. Since we can copy to columns that are not there yet (and thus they are created then), wouldn’t it make sense to also automatically make them visible when being automatically created?
So probably a renoise.song().tracks[1].visible_note_columns = renoise.song().tracks[1].visible_note_columns + 1 when adding a new one will work as well.