title: How to make TextBox lose its focus?
body: <p>How to make <code>TextBox</code> lose its focus and hide onscreen keyboard when user touches <code>Enter</code> virtual key?</p>
  
  <pre><code>    private void TheName_KeyDown(object sender, KeyRoutedEventArgs e) {
          var tb = sender as TextBox;
          if (e.Key == Windows.System.VirtualKey.Enter) {
              // ... tb.LooseTheFocus_PLEASE(); !???
          }
      }
  </code></pre>