multiple windows with tab views

[ccunning at math.ohio-state.edu (Chad Cunningham)]

I'm trying to wrap my brain around how I would write an app whose 
interface can have multiple windows, each with a tab view. So I have a 
MainController which handles primarily actions from the menus. Then I 
have a nib for the window and a controller for that. Now, how do I have 
the controller be able to open multiple windows, and how can it access 
the TabView in the active window? Do I need to subclass 
NSWindowController? I'm getting confused about how all this should go 
together and what should be controlling what, any tips appreciated :)