Hi,
I am still on BIAB 2008,so perhaps my request has been addressed already.
Back in the early 90s I enjoyed using an Amiga music program called Superjam.
This software has long since passed away as The Amiga eventually did.
I had loads of fun superjamming and composing the basic outlines of my songs.
One feature I really liked was SJ's ability to "locked bars/measures" when I heard something tastily generated.This locking of bars would preserve the bits I really liked while the software went on to another round of composing.

Regards,
Tony C