title: How check if action exsist in Controller Plugin preDispatch
body: <p>I have two modules (default and mobile) the module mobile is a rewrite the default portal in jquery mobile but with much less controllers and actions!
  I thought of write a controller plugin that check if controller and action exist in module mobile, if not I would like overwrite the module mobile to default.
  I try this:</p>
  
  <pre><code>public function dispatchLoopStartup(Zend_Controller_Request_Abstract $request)
  {
      $dispatcher = Zend_Controller_Front::getInstance()-&gt;getDispatcher();
      if ($request-&gt;getModuleName() == 'mobile') {      
          if (!$dispatcher-&gt;isDispatchable($request)) {
              // Controller or action not exists
              $request-&gt;setModuleName('default');
          }
      }
      return $request;
  }
  </code></pre>
  
  <p>but <code>$dispatcher-&gt;isDispatchable($request)</code> return always <code>true</code> though the action not exist! :S 
  and i receive "Action <code>foo</code> does not exist and was not trapped in __call()"</p>
  
  <p>How can I do?
  Thanks</p>