OneWay binding for ToggleButton's IsChecked property in WPF

Question

I have a ToggleButton with its IsChecked property bound to a property using a OneWay binding.

Answer 1

There is a simple and elegant way to solve the original poster's problem - replacing IsChecked property of the ToggleButton with an attachable property that will set IsChecked of the button in its change handler:

namespace TBFix
{
  public class TBExtender
  {
    public static readonly DependencyProperty IsCheckedProperty =
      DependencyProperty.RegisterAttached("IsChecked", 
                                          typeof(bool),
                                          typeof(TBExtender),
                                          new PropertyMetadata(OnChanged));

    public static bool GetIsChecked(DependencyObject obj)
    {
      return (bool)obj.GetValue(IsCheckedProperty);
    }
    public static void SetIsChecked(DependencyObject obj, bool value)
    {
      obj.SetValue(IsCheckedProperty, value);
    }

    private static void OnChanged(DependencyObject o,
                                  DependencyPropertyChangedEventArgs args)
    {
      ToggleButton tb = o as ToggleButton;
      if (null != tb)
        tb.IsChecked = (bool)args.NewValue;
    }
  }
}

XAML then will look like this:

EDIT: The OP solution does not work, because when the button is pressed the IsChecked property is set in the code (this is the way MS implemented ToggleButton control) - setting the property removes the binding from it and so it stops working.

By using attached property we can overcome this problem because it is never assigned a value in code and so the bindings stays intact.