title: Set TextBlock Text if Windows 10 uses dark theme (UWP)
body: <p>I want to set the text of a TextBlock if the windows 10 user uses the dark/light theme. I have tried</p>
  
  <pre><code>RequestedTheme == ElementTheme.Dark
  </code></pre>
  
  <p>but it doesn't work.</p>
  
  <p>EDIT:
  I want to set it like this</p>
  
  <pre><code>if(user uses dark them)
  {
      mTextBlock.Text = "Dark"
  }
  elseif(user uses light theme)
  {
     mTextBlock.Text = "Light"
  }
  </code></pre>