Prism 7 uses the Versions and Resume features of OS X to make it easier to get your work done without thinking about saving files. Your work is saved as you go, with no need to ever click the Save button (although you can). Automatic backup is handled by the Mac Versions and Resume feature, and is no longer handled by code we wrote.
This is a change Apple introduced a few years ago. If you use iWork (Pages, Numbers, Keynote), you already know about Versions and Resume. If you don't use iWork, spend a minute reading about these features to avoid frustration.