I found a blog post that gives a rundown on the evolution of MVC (https://billkrat.wordpress.com/2010/12/23/hello-world/) and links something similar to the document I had originally read (http://heim.ifi.uio.no/~trygver/1979/mvc-2/1979-12-MVC.pdf). I think I had originally found something that was more of a prototype of this document, but the wording appears to be the same and more succinct. The blog post also links to an earlier version of the MVC model that included a fourth part, a "Thing".

One thing I found interesting in the blog article was the notion of "smart controls", but I can rationalize that away as another MVC module; after all, the Windows OS itself is handling all the interesting behavior, and the GUI app is borrowing the behavior. Depending on the toolkit that interfaces with the "smart controls", we get access to events (mousedown, keypress, etc) that can serve as input to one of our application's controllers.