title: Class defined without specifying a base class?
body: <p>Simple inheritance that I've done a million times:</p>
  
  <pre><code>@class AGWindowView;
  
  @interface HelperView : AGWindowView
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>Class "HelperView" defined without specifying a base class.
  </code></pre>
  
  <p>Well, obviously I am specifying a base class. What is going on here? Is there some way AGWindowView would not allow itself to be subclassed?</p>