[Eug-lug] Cocoa programming question

[perdurabo]

I know that one or two of you here are fluent in Cocoa, so I'll try
this question on you:

I'm writing an app that has two controllers: AppController (subclass
of NSObject) and PreferencesController (which is a subclass of
NSWindowController and contains a preferences panel (NSPanel).

AppController sits in MainMenu.nib and PreferencesController and its
related NSPanel sits in Preferences.nib. AppController creates an
instance of PreferencesController when it needs to.

I need to call AppController's stopTimer: selector from a
PreferencesController action, but haven't found a solid way of doing
this. Google searches, etc provide several different ways of kind of
doing this, but nothing solid that seems "right".

Is there some global variable that points to AppController? The
Hillegass book doesn't cover this aspect.

If you're an advanced Cocoa programmer: should I scrap the current
design (PreferencesController deal in another NIB file, this was
recommended by Hillegass and others for some reason) and move
everything into MainMenu.nib?

TIA,
per