I actually disagree from a systems engineer perspective: The program doesn’t actually know shit if those bits hit any permanent medium, just that the OS told them “I’ll take care of it” it could be sitting in a write back cache when you save, see the “write complete” and rip the power and that’s all gone now. Basically, I don’t like promising durability when it’s not really there.

Check for an asterisk after the file name (in the tab/title bar), it means "unsaved changes".