Ajax.Responders.register({
   onCreate: function() {
     new Effect.Appear('ajax_loader', { duration: 0.3, to: 0.5 });
     },
   onComplete: function(request, transport, json) {
     if (0 == Ajax.activeRequestCount) {
       new Effect.Fade('ajax_loader', { duration: 0.3, from: 0.5 });
     }
     if(!request.success()) {
       var errorMapping = $H({
         400: ['Bad Request', 'The request contains bad syntax or cannot be fulfilled.'],
         401: ['Authorization Required', 'You need to authenticate to access this page.'],
         403: ['Forbidden', 'The request was a legal request, but the server is refusing to respond to it.'],
         404: ['Page Not Found', 'The requested resource could not be found.'],
         405: ['Method Not Allowed', 'A request was made of a resource using a request method not supported by that resource; for example, using GET on a form which requires data to be presented via POST, or using PUT on a read-only resource.'],
         406: ['Not Acceptable', 'The action you tried to perform on this resource was considered unacceptable.'],
         415: ['Unsupported Media Type', 'The media type you are requesting is unsupported.'],
         422: ['Unprocessable Entity', 'The request was well-formed but was unable to be followed due to semantic errors.'],
         500: ['Application Error', 'An error occurred in the application code. Report sent.'],
         503: ['Service not available', 'The webserver did not respond to the request.'],
         505: ['HTTP Version Not Supported', 'The requested version is not available on this server.']
       });

       var errorMessage = errorMapping.get(transport.status) || ['Unknown Error', 'An error occurred, but could not be determined correctly.'];

       if (transport.responseJSON && transport.responseJSON.error)
          errorMessage = [transport.responseJSON.error.title, transport.responseJSON.error.message]

       var notifyUser = new GrowlNotifier({
         title: errorMessage[0],
         message: errorMessage[1],
         image: "/images/elements/growl_warning.png",
         type: 'error'
       });
     }
   }
});