Problem: Meta Instr. Macros allows to select the index of instrument "FF"

@taktik, if you want to correct small details detected, here is another one.
The range of the instrument index reaches FE. FF seems reasonable to think that it will never be used, because it does not exist. Therefore, it is useless to be able to select it from the Meta Instr. Macros ". It does not seem to be useful. To avoid selecting an instrument, there is the value -1, right?

This seems like a silly detail, but you may want to check / adjust it…