title: UWP extend into title bar - default title bar converting back button
body: <p>In my UWP app, I trying to get the back button into the title bar, which I have done many times in the past. This time, the trouble I'm facing is that the default title bar doesn't seem to be going away, and is hovering over my button so I cannot press it. I tried creating a custom title bar with margins, but that didn't fix it. Here's the extending into title bar...:</p>
  
  <pre><code>var coreTitleBar = CoreApplication.GetCurrentView().TitleBar;
  coreTitleBar.ExtendViewIntoTitleBar = true;
  </code></pre>
  
  <p>...and the custom title bar:</p>
  
  <pre><code>var titleBarGrid = new Grid()
  {
      Background = new SolidColorBrush(Colors.Transparent),
      HorizontalAlignment = HorizontalAlignment.Stretch,
      VerticalAlignment = VerticalAlignment.Top,
      Height = 48,
      Margin = new Thickness(50, 0, 150, 0),
  };
  Window.Current.SetTitleBar(titleBarGrid);
  </code></pre>
  
  <p>These are being set in the App.xaml.cs.</p>
  
  <p>How do I remove/overwrite the default title bar?</p>