title: Two Way Data-binding is not Updating for ComboBox & ToggleButton?
body: <h1>Problem</h1>
  
  <p>I have a <code>ComboBox</code> and a <code>ToggleButton</code> on <code>MainWindow</code> with two-way bindings on their <code>SelectedIndex</code> and <code>IsChecked</code> properties, respectively. The properties they bind to are DependencyProperties (DP) and I have a breakpoint on the setters but the debugger never stops at either. I should note that the bindings should work as the Initialisers on the DPs work and converters also work. Also nothing of concern is VS's Output Window.</p>
  
  <h1>XAML</h1>
  
  <pre><code>&lt;ToggleButton x:Name="tbSortDirection" Width="25" IsChecked="{Binding Path=SortDirection,Converter={StaticResource LDB},Mode=TwoWay,ElementName=mwa,UpdateSourceTrigger=PropertyChanged}"&gt;
      &lt;ed:RegularPolygon Fill="#FF080808" Height="5" UseLayoutRounding="True" Margin="-2,0,0,0" PointCount="3" Width="6"/&gt;
  &lt;/ToggleButton&gt;                 
  &lt;ComboBox x:Name="cbSort" Width="100" VerticalAlignment="Stretch" Margin="-5,0,0,0"  SelectedIndex="{Binding SelSortIndex,Mode=TwoWay,ElementName=mwa,UpdateSourceTrigger=PropertyChanged}" IsSynchronizedWithCurrentItem="True" &gt;
      &lt;ComboBoxItem Content="a"/&gt;
      &lt;ComboBoxItem Content="b"/&gt;
      &lt;ComboBoxItem Content="v"/&gt;
      &lt;ComboBoxItem Content="f"/&gt;
  &lt;/ComboBox&gt; 
  </code></pre>
  
  <h1>Code-Behind (DPs)</h1>
  
  <pre><code>public ListSortDirection SortDirection
  {
      get { return (ListSortDirection)GetValue(SortDirectionProperty); }
      set // BreakPoint here
      {
          MessageBox.Show("");
          SetValue(SortDirectionProperty, value);
          UpdateSort();
      }
  }
  
  public static readonly DependencyProperty SortDirectionProperty =
      DependencyProperty.Register("SortDirection", typeof(ListSortDirection), typeof(MainWindow), new PropertyMetadata(ListSortDirection.Ascending));
  
  
  
  public int SelSortIndex
  {
      get { return (int)GetValue(SelSortIndexProperty); }
      set // BreakPoint here
      {
          MessageBox.Show("");
          SetValue(SelSortIndexProperty, value);
          UpdateSort();
      }
  }
  
  public static readonly DependencyProperty SelSortIndexProperty =
      DependencyProperty.Register("SelSortIndex", typeof(int), typeof(MainWindow), new PropertyMetadata(1));
  </code></pre>