title: WriteableBitmapEx not working for C# metro app
body: <p>I downloaded WriteableBitmapEx for winrt (win 8 metro).
  I added a reference to the dll with the extension methods , used them in my code , every thing compiles ok.</p>
  
  <p>The problem is that the extension methods have no effect.
  Here is part of my code:</p>
  
  <pre><code>WriteableBitmap wb = new WriteableBitmap((int)pictureSize.Width,   (int)pictureSize.Height);
  wb.SetSource(fileStream);
  var newWB = wb.Flip(FlipMode.Vertical);
  ImageControl.Source = newWB;     
  newWB.Invalidate(); 
  </code></pre>
  
  <p>The image does not appear on the screen.
  But if I try to draw something on the image , like a line, the image appears on the screen unchanged.</p>
  
  <p>thank you!</p>