Windows was document-centric in other respects, too. For example, the standard UX guidelines defined three types of apps: dialog, single-document interface, and multi-document interface. Most apps were actually expected to be of the last two varieties, and the guidelines covered a lot of points on how it was all supposed to look. And when it came to implementation, frameworks like MFC were designed around that concept as well, with the ability to automatically handle things like multiple views into the same document.