title: How to detect a Pivot item is selected in Windows Phone 7
body: <p>I am implementing the Pivot control in Windows Phone 7.</p>
  
  <p>I want to know which Pivot item is selected and active after the user does a swipe gesture.</p>
  
  <p>How to detect the swipe gesture event related to Pivot control?</p>
  
  <p>Which delegate method should I use ?</p>