title: How to display a Modal form in Windows Phone 8.1
body: <p>I have a Windows 8.1 WinRT app.
  I want to have a XAML control in which i can have xaml controls like a button, textblock, listbox, etc.</p>
  
  <p>I want to be able to load this XAML control in any page from the app. But i want it to appear as a modal, on top of the current page  over a black overlay.</p>
  
  <p>How can i load a Xaml control on top of the current page?
  Is there a way ot interact from this overlay with the other controls in the current page?</p>
  
  <p>Example: while on a page, i want to open the modal and tap a button which will fill a form in the current page with test data.</p>