title: Set layout from responder?
body: <p>I am trying to figure out how to set the layout from a custom made responder. I want to use the request.xhr? to set the layout for render to 'ajax'.  Does anybody know how to do that? 
  I am using Rails 3 and I have a responder like this:</p>
  
  <pre><code>module AjaxLayoutResponder
    def to_html
      if request.xhr?
        # do something here to change layout...
      end
      super
    end
  end
  </code></pre>
  
  <p>It seem to me like a responder is the best way to accomplish this 'ajax' layout switching.</p>