title: Radiobutton "Checked" method doesn't work
body: <p>I have an unknown problem with building my first UWP App.</p>
  
  <p>On button onclick method I want to check if one of checkboxes is checked and if yes I want to open a new frame:</p>
  
  <pre><code>namespace IDG
  {
      /// &lt;summary&gt;
      /// An empty page that can be used on its own or navigated to within a Frame.
      /// &lt;/summary&gt;
      public sealed partial class MainPage : Page
      {
          public MainPage()
          {
              this.InitializeComponent();
          }
  
          private void bt_start_Click(object sender, RoutedEventArgs e)
          {
              if (rb_quiz.Checked)
              {
                  this.Frame.Navigate(typeof(Page2));
              }
          }
      }
  }
  </code></pre>
  
  <p>Visual Studio marks error on that line:
  <code>if (rb_quiz.Checked)</code></p>
  
  <p>The popup says: </p>
  
  <blockquote>
    <p>The Event '<code>ToggleButton.Checked</code>' can only appear on the left hand side of += or -"</p>
  </blockquote>
  
  <p>I have checked "<code>==Checked</code>" or "<code>isChecked</code>". But nothing works. My <code>radiobutton</code> is called <code>rb_quiz</code>.</p>