title: WPF Bind checkbox to bool?
body: <p>I have a WPF checkbox binded to ViewModel nullable boolean property. I am setting this property to false or true in Constructor, to avoid Interminent state but no matter what I do the Initial state of checkbox stays grayed. The binding working just fine since once I change the state by clicking the checkbox on UI I am getting controls values (true/false). Any Ideas?</p>
  
  <p><strong>XAML:</strong></p>
  
  <pre><code>&lt;CheckBox Margin="0,4,0,3"
            VerticalAlignment="Center"
            Content="Mutual"
            IsChecked="{Binding MutualChb}" /&gt;
  </code></pre>
  
  <p><strong>ViewModel:</strong></p>
  
  <pre><code>public ContstrutorViewModel()
  {
      MutualChb = true;
  }
  
  private bool? _mutualChb;
  public bool? MutualChb
  {
      get { return _mutualChb; }
      set
      { 
          _mutualChb = value; 
          _mutualChb = ( _mutualChb != null ) ? value : false;
          OnPropertyChanged("MutualChb");
      }
  }
  </code></pre>