Put the backup file in a separate folder
The hidden backup files automatically generated when saving are a significant irritant for me, often causing confusion (I can't count the number of times I've attempted to open one of them by mistake instead of the real file).
Please don't tell me to turn off hidden files. I exercise complete control over my system, so of course I have it set to show hidden files, and these things are a significant annoyance. As it is, I spend a lot of time deleting them so they don't cause confusion, thus losing the safety net they are meant to provide. But it's worth it to preserve my workflow.
Surely a good compromise would be to place these hidden backups in a separate folder which the user can control from Preferences | General | Folders.