Select multiple instruments to add notes

[Lopyt]

Would be nice if we could select a few instruments, especially with the clones, and when you click or erase it adds or removes it for all instruments in that slot!

[JOwen]

I agree, this would be nice. 

also (and this is far from necessary) it would be cool if you could set an "offset" i.e. if you have clean guitar and 8-bit sine selected, when you place a note, it places the clean guitar where you clicked and places the 8-bit sine an octave lower. not sure if this is a dumb idea or not though (my suggestion, i mean)