title: UWP update Button content in UIThread
body: <p>I have a button that does a backgroud task (it searches lyrics from the Internet for all music files). And it updates the button content by incrementing the counter as it fetches the lyrics.</p>
  
  <pre><code>    private async void AddLyrics_Click(object sender, RoutedEventArgs e)
      {
          await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, async () =&gt;
          {
              string format = Helper.LocalizeMessage("PostParenthesis");
              HyperlinkButton button = (HyperlinkButton)sender;
              int count = MusicLibraryPage.AllSongs.Count;
              for (searchLyricsCounter = 1; searchLyricsCounter &lt; count + 1; searchLyricsCounter++)
              {
                  Music music = MusicLibraryPage.AllSongs[searchLyricsCounter - 1];
                  string lyrics = await music.GetLyricsAsync();
                  //if (string.IsNullOrEmpty(lyrics))
                  //{
                  //    lyrics = await Controls.MusicLyricsControl.SearchLyrics(music);
                  //    await music.SaveLyricsAsync(lyrics);
                  //}
                  System.Diagnostics.Debug.WriteLine(searchLyricsCounter);
                  button.Content = string.Format(format, addLyricsContent, searchLyricsCounter + "/" + count);
              }
              searchLyricsCounter = 0;
              button.Content = Helper.Localize("AddLyrics");
              Helper.ShowNotification("SearchLyricsDone");
          });
      }
  </code></pre>
  
  <p>The button is located in a page (SettingsPage) of a Frame in the MainPage. After I switch to another page  and change back to SettingsPage, the button stops updating the content, although the thread is still running.</p>
  
  <p>How can I keep the button content updating?</p>