title: scrollviewer to scroll to textbox position
body: <p>How I can get behavior of form in windows Phone like <code>Settings &gt;&gt; Mobile Network &gt;&gt; EditAPN</code>.
  In this page it have many textboxes in scrollviewer. When user taps on any textbox and its get focus then the page scrolls up and header remains constant and SIP keyboard shown. And when user lost the focus from this text box then page comes to its normal state and SIP keyboard hides and header remains unchanged. I want to achieve this behavior. I placed some textboxes in scrollviewer and on each textbox got focus event I am doing this.</p>
  
  <pre><code>this.Scroller.ScrollToVerticalOffset(this.txtbox1.ActualHeight); 
  this.Scroller.UpdateLayout();
  </code></pre>
  
  <p>But Its not working for me. Any help will be appreciates</p>