title: Overlay over multiple pages on Windows Phone 8
body: <p>I trying to build a Windows Phone 8 Application which is able to sync data from a webservice. </p>
  
  <p>While I'm syncing the data I want to display a little Popup / overlay / flyout but I still want to be able to navigate between my pages while my overlay persists between this pages.</p>
  
  <p>I did this successfully with a Windows RT App: I simply added a Frame-Control on a RootPage which also display the flyout. I navigated then within this frame and the flyout was always there. </p>
  
  <p>How can I achieve this goal within a Windows Phone 8 Application?</p>