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

Question

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?

Answer 1

So, I found the problem (posting the question in SO seems to be a condition to finding the solution, always...)
The offending line was not setting the delegate, but what I was doing to the window after entering fullscreen mode. In particular, as soon as I commented out the following line
[window setStyleMask:NSBorderlessWindowMask]; in the code below:
- (void) windowDidEnterFullScreen:(NSNotification*) notification
{
NSWindow* window = [self window];
NSRect mainDisplayRect = [[NSScreen mainScreen] frame];
[window setStyleMask:NSBorderlessWindowMask];
[window setContentSize:mainDisplayRect.size];
[window setLevel:NSMainMenuWindowLevel + 1];
[window makeKeyAndOrderFront:self];
NSRect windowFrame = [window frame];
windowFrame.origin.x = 0;
windowFrame.origin.y = 0;
[window setFrame:windowFrame display:YES];
}
...the expected enter/exit fullscreen mode behaviour was fixed.