/// <summary>
/// Called when SourceProperty is invalidated on "d."
/// </summary>
/// <param name="d">The object on which the property was invalidated.</param>
/// <param name="e">Argument.</param>
private static void OnSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
CollectionViewSource ctrl = (CollectionViewSource)d;
if (!IsSourceValid(e.NewValue))
{
throw new InvalidOperationException("Unsupported type of source for a collection view.");
}
ctrl.OnSourceChanged(e.OldValue, e.NewValue);
ctrl.EnsureView();
}