Exit fullscreen breaks in Mountain Lion after changing window's delegate

Exit fullscreen breaks in Mountain Lion after changing window's delegate

I created my project from the Xcode template for non-document based Cocoa
Application.
I have a custom NSWindowController that, after being instantiated on
startup, takes possession of the default window (defined in MainMenu.xib).
If I leave the app delegate's window as it is, I can toggle fullscreen
mode with command-F (set to -toggleFullscreen: in a menu item), or I can
exit from fullscreen by pressing ESC.
Once I set my window controller as the window's delegate (I need this to
do some OpenGL adjustments on enter/exit fullscreen, etc.), I can still
enter fullscreen by pressing command+F, but I can no longer exit
fullscreen (save for command+tab to another app, or command+Q).
Also, the Apple docs mention setting the menu action to -toggleFullscreen:
and the target to nil. How is this last part done in Interface Builder? (I
connected the action to First Responder's -toggleFullscreen:)
What should I do?