title: Passing parameter into Task's Action delegate result in exception
body: <p>Hi i'm trying to create a thumbnail using the TPL with the Expression's Behavior but i Hit the trying to access on a different thread exception at the File.OpenRead(uriSource) line. I'm trying to pass a UI Thread's parameter into a background task's Thread which causes the error I think... how can i solve this problem?</p>
  
  <pre><code>Task.Factory.StartNew(() =&gt; RenderThumb(UriSource)).ContinueWith((bs) =&gt;
          {....}, TaskScheduler.FromCurrentSynchronizationConext());
  
  private BitmapSource RenderThumb(string uriSource)
      {
  
          Stream imageStream = File.OpenRead(uriSource);
          ...
          return bitmapSource;
      }
  </code></pre>