Breaking Down NSTabView Into Files

As my Cocoa app comes along, my NSWindowController is becoming huuuuuuuuuuge. My window has an NSTabView, and each tab therein has its own NSViewController (they all have submenus) and its own methods. So, my WindowController.m seems to stretch well beyond what it's supposed to because of tabs.

Sadly, examples of NSTabView are quite simple. They don't need any restructuring. So, here I am 开发者_开发技巧seeking advice. How can I pull tab-specific content out of the window controller and into their own dedicated objects?

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See the example in this Apple Discussions thread: Tab Controllers?