title: app.showMessage in compositionComplete no appears
body: <p>I need to show a message in "compositionComplete", but the next code no work:</p>
  
  <pre><code>function compositionComplete(view, parent) {
          app.showMessage('This is a message.', 'Demo');
      }
  </code></pre>
  
  <p>The view was blocked and the <code>app.showMessage</code> didn't appear.</p>
  
  <p>I use Breeze 1.4.1, Durandal 2.0, Knockout 2.3.0, Bootstrap 3.0, jquery 2.0.3 and in the shell <code>cacheViews:true</code>.</p>
  
  <p>javascript console only show:</p>
  
  <pre><code>Binding plugins/messageBox 
  MessageBox {message: "This is a message.", title: "Demo", options: Array[1], __dialog__: Object, selectOption: function…}
   system.js:75
  </code></pre>
  
  <p>I review the console and the problem appeared when exist errors of databind with ko or Q. But I need to show these errors with 'app.showMessage'.</p>
  
  <p>I test in IE 10, Firefox 23, Google Chrome 29 but the problem persist in three browsers.</p>