The problem with your category approach is that NSView is not a
concrete class, it is an abstract superclass meaning it might be
implemented in appkit as a class cluster.
Errr... no. You can easily create a plain NSView in Interface
Builder around other views, so it's definitely not abstract, and I've
yet to see any documentation stating that NSView was a class cluster.
Can you give me a URL where you heard NSView was a class cluster?