title: Mahapps ShowProgressBarAsync only shows after my loading task is finished
body: <p>I'm trying to use the mahaps progress bar dialog for my application to trigger when a task starts that would normally freeze the application for a few seconds. </p>
  
  <pre><code>private void Button_Click(object sender, RoutedEventArgs e)
  {
      LoadingDialog();
  
      SaveAndLoadData.SaveUserData(ApplicationData.UserData);
      MainWindowLogic.LogIntoWebsites();
  }
  
  private async void LoadingDialog()
  {
      var controller = await this.ShowProgressAsync("Logging In...", "");
  }
  </code></pre>
  
  <p>The Loading dialog doesn't actually pop up till after my <code>LogIntoWebsites()</code> method has finished. I'm getting a feeling that I am not understanding asynchronous right, and that I'm definitely doing something wrong here.</p>
  
  <p>Ideas?</p>