WPF - Bindable PasswordBox

using System.Windows;
using System.Windows.Controls;

namespace CustomControl
{
    public class BindablePasswordBox : Decorator
    {
        /// <summary>
        /// The password dependency property.
        /// </summary>
        public static readonly DependencyProperty PasswordProperty;

        private bool isPreventCallback;
        private RoutedEventHandler savedCallback;

        /// <summary>
        /// Static constructor to initialize the dependency properties.
        /// </summary>
        static BindablePasswordBox()
        {
            PasswordProperty = DependencyProperty.Register(
                "Password",
                typeof(string),
                typeof(BindablePasswordBox),
                new FrameworkPropertyMetadata("", FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, new PropertyChangedCallback(OnPasswordPropertyChanged))
            );
        }

        /// <summary>
        /// Saves the password changed callback and sets the child element to the password box.
        /// </summary>
        public BindablePasswordBox()
        {
            savedCallback = HandlePasswordChanged;

            PasswordBox passwordBox = new PasswordBox();
            passwordBox.PasswordChanged += savedCallback;
            Child = passwordBox;
        }

        /// <summary>
        /// The password dependency property.
        /// </summary>
        public string Password
        {
            get { return GetValue(PasswordProperty) as string; }
            set { SetValue(PasswordProperty, value); }
        }

        /// <summary>
        /// Handles changes to the password dependency property.
        /// </summary>
        /// <param name="d">the dependency object</param>
        /// <param name="eventArgs">the event args</param>
        private static void OnPasswordPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs eventArgs)
        {
            BindablePasswordBox bindablePasswordBox = (BindablePasswordBox) d;
            PasswordBox passwordBox = (PasswordBox) bindablePasswordBox.Child;

            if (bindablePasswordBox.isPreventCallback)
            {
                return;
            }

            passwordBox.PasswordChanged -= bindablePasswordBox.savedCallback;
            passwordBox.Password = (eventArgs.NewValue != null) ? eventArgs.NewValue.ToString() : "";
            passwordBox.PasswordChanged += bindablePasswordBox.savedCallback;
        }

        /// <summary>
        /// Handles the password changed event.
        /// </summary>
        /// <param name="sender">the sender</param>
        /// <param name="eventArgs">the event args</param>
        private void HandlePasswordChanged(object sender, RoutedEventArgs eventArgs)
        {
            PasswordBox passwordBox = (PasswordBox) sender;

            isPreventCallback = true;
            Password = passwordBox.Password;
            isPreventCallback = false;
        }
    }
}