window.setTimeout(function() {
        if (req.status === 200)
          onResult(isBinary ? req.response : req.responseText);
        else
          onResultFail(req.status);
      }, 0);
    };
    req.send(null);
  }

  function onResultFail(err) {
    var overlay = new tr.ui.b.Overlay();
    overlay.textContent = err + ': ' + url + ' could not be loaded';
    overlay.title = 'Failed to fetch data';