title: Issue getting msgBox work in Google Apps Script web app
body: <p>I have a little problem with Google Apps Script web app. The following script sample works perfectly in web app once its inside docs. But as a stand alone app in a browser, I keep having error messages. Please how can I make the <strong>"Browser.msgBox (prompt)"</strong> work in a browser?</p>
  
  <p>In case you'd like to see the error message, the app can be accessed <a href="https://script.google.com/macros/s/AKfycbzCvQK8yNeZH8FPrtYwnKMgJSRI2QqEeTYdq8TB4xpb3fDmn5k/exec" rel="nofollow">here</a>.</p>
  
  <pre><code>// Script-as-app template.
  function doGet() {
  var app = UiApp.createApplication();
  
  var button = app.createButton('Click Me');
  app.add(button);
  
  var label = app.createLabel('The button was clicked.')
               .setId('statusLabel')
               .setVisible(false);
  app.add(label);
  
  var handler = app.createServerHandler('myClickHandler');
  handler.addCallbackElement(label);
  button.addClickHandler(handler);
  
  return app;
  }
  
  function myClickHandler(e) {
  var app = UiApp.getActiveApplication();
  
  var label = app.getElementById('statusLabel');
  label.setVisible(true);
  
  Browser.msgBox("hello world");//THIS  IS MY PROBLEM!!!
  
   app.close();
   return app;
   }
  </code></pre>