title: How to save existing StorageFile using FileSavePicker?
body: <p>I'm trying to save existing file to another place. It's some kind of copy, but I want to allow choosing of new destination to user with FileSavePicker.
  Here is my code:</p>
  
  <pre><code>StorageFile currentImage = await StorageFile.GetFileFromPathAsync(item.UniqueId);
  var savePicker = new FileSavePicker();
  savePicker.FileTypeChoices.Add("JPEG-Image",new List&lt;string&gt;() { ".jpg"});
  savePicker.FileTypeChoices.Add("PNG-Image", new List&lt;string&gt;() { ".png" });
  savePicker.SuggestedSaveFile = currentImage;
  savePicker.SuggestedFileName = currentImage.Name;
  var file = await savePicker.PickSaveFileAsync();
  </code></pre>
  
  <p>After that the file will be created, but it empty (0 KB). How to save file correctly?</p>