Add backward compatibility to Mac OS 10.6

I adopted INAppStoreWindow in my application (targeting Mac OX >= 10.6) and I found it crashed on 10.6 so I modified code to prevent 'fullscreen' related feature. It would be great that if you set main window's 'Full Screen' property to 'Unsupported' in the XIBs and add some code(suggested  below) to make sure it runs well on 10.6.
(I couldn't make changes on XIB directly because I use Xcode with old version currently)

[suggested code]

// this can be added any init code for the main window
if ([self.window respondsToSelector:@selector(toggleFullScreen:)]) {
		self.window.collectionBehavior &= !NSWindowCollectionBehaviorFullScreenAuxiliary;
		self.window.collectionBehavior |= NSWindowCollectionBehaviorFullScreenPrimary;
	}