title: Windows Phone Keyboard Back-key press event?
body: <p>I am working on a windows phone application.</p>
  
  <p><br> I noticed that after I show up a textbox and a keyboard, if I press physical "back" key, the keyboard will hide, and press again it will go back to previous page.</p>
  
  <p>But I want the page to navigate to previous page when the "back" key is press the first time. So its like the keyboard is up, when I press back key, it directly go back to the previous page.</p>
  
  <p>I tried to implement the <code>BackKeyPressed</code> event handler of the page but it does not seem work, since it is not called when the first time back key is pressed.</p>
  
  <p>Anyone has any good idea with this? thank you</p>