NSDocumentController - Reusing a single window across multiple documents

A further twist to having a single document visible at any one time is that I would like to keep a single window and reuse it. The way I have done this is as follows

• When I get the NSApplicationWillFinishLaunchingNotification I create the window controller and window. I do this by reading in a nib file that has my subclass of a window controller and a window.
• In the makeWindowControllers method of my document subclass I call addWindowController to add my global window controller.

And that is about it.