Maybe could have it work on a cloned temp file, and then autosaving on losing focus. Opening the same real-file would lead to the same temp-file. Might be able

Maybe could have it work on a cloned temp file, and then autosaving on losing focus. Opening the same real-file would lead to the same temp-file. Might be able to make manual :w save the temp to the real, but may be better to have it as a separate command.