      *  Called by the default <code>prepareForPlay()</code> implementation, 
      *  this method is responsible for creating the Spark effect 
      *  played on the action bar when the transition starts.  
-     *  This method should be overridden by sub classes if a custom action bar 
+     *  This method should be overridden by subclasses if a custom action bar 
      *  effect is required.  
      *  By default, this method returns a basic action bar effect.
      * 

    private var _startView:View;
    
    /**
     *  Reference to the currently active view of the view navigator, 
     *  set by the owning view navigator. 
     *  This property can be null.
     * 
     *  @langversion 3.0

 *  The ViewTransitionBase class is the base class for all view transitions.  
 *  It is not intended to be used as a transition on its own.
 *  In addition to providing common convenience and helper methods used by 
 *  view transitions, this class provides a default action bar transition 
 *  sequence.
 * 
 *  <p>When a view transition is initialized, the owning view navigator 
