I'm grabbing a list of documents (and then their fileURLs) at quit by
putting code in applicationWillTerminate to cycle through
NSDocumentController's documents method. This works, usually.
Specifically, it only works when documents have already been saved.
If a document throws up the not saved/unsaved changes sheet, then
when it finally gets to applicationWillTerminate the array of open
documents is empty.
How can I get a list of open documents at quit and/or get it before
NSDocumentController does whatever magic it's doing to get to the
quit event before me?