I don't think the distinction really matters. In this context, you can think of an operating system as a "master app" that has escalated privileges for things such as root-level access to system functions and the hardware.
>> I mean sure, your program might be the ants pants, but what happens when the user needs to enter data while viewing another document?
This soon won't even be an issue, because the data will not have to be manually transferred between documents by a human user.