Often I don't know that I'm going to want to save as a new version until half way through. I some times open the original intending to make minor, non-destruct

Often I don't know that I'm going to want to save as a new version until half way through. I some times open the original intending to make minor, non-destructive, changes, then end up making bigger changes and think "hmm, I'd better save as a different file in case I need the old one later". I think to advance to the world of auto-save, one also needs to much more visibly advance to the world of file versioning where it's really clear to the user whether their changes are ultimately destructive or not.