delete unused instruments in selection

Would be very handy if there would also be an option to “delete unused instruments in selection” of the instrument box.

What does the limitation of “selection” do here? Instruments are globally available.

I would like to suggest “select unused instruments” instead delete it, since sometimes you simply want to know if an instrument is in use or not, without deleting it. That would then require multiple selection in the instrument box (and in the api).