title: Binding to an NSDictionary's "allValues" array
body: <p>Am I misunderstanding something about bindings? I bind (an NSArrayController's content) to an NSDictionary's "allValues" array, and it thinks it's empty. I bind to a random object with a property that I've set to be that same NSDictionary's "allValues" array, and it works fine.</p>
  
  <p>Is this expected behavior, or am I doing something wrong? Furthermore, if this is expected, what is the standard way to deal with this? Making relatively purposeless objects just to hold arrays in properties so I can bind to them seems ugly.</p>