VideoConcat/Helpers/PasswordBoxHelper.cs

// PasswordBoxHelper.cs
using System.Windows;
using System.Windows.Controls;

namespace VideoConcat.Helpers
{
    public static class PasswordBoxHelper
    {
        public static readonly DependencyProperty BoundPasswordProperty =
            DependencyProperty.RegisterAttached("BoundPassword", typeof(string), typeof(PasswordBoxHelper),
                new PropertyMetadata(string.Empty, OnBoundPasswordChanged));

        public static readonly DependencyProperty BindPasswordProperty =
            DependencyProperty.RegisterAttached("BindPassword", typeof(bool), typeof(PasswordBoxHelper),
                new PropertyMetadata(false, OnBindPasswordChanged));

        public static string GetBoundPassword(DependencyObject dp)
        {
            return (string)dp.GetValue(BoundPasswordProperty);
        }

        public static void SetBoundPassword(DependencyObject dp, string value)
        {
            dp.SetValue(BoundPasswordProperty, value);
        }

        public static bool GetBindPassword(DependencyObject dp)
        {
            return (bool)dp.GetValue(BindPasswordProperty);
        }

        public static void SetBindPassword(DependencyObject dp, bool value)
        {
            dp.SetValue(BindPasswordProperty, value);
        }

        private static void OnBoundPasswordChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is PasswordBox passwordBox)
            {
                passwordBox.Password = (string)e.NewValue;
            }
        }

        private static void OnBindPasswordChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (d is not PasswordBox passwordBox)
            {
                return;
            }

            if ((bool)e.OldValue)
            {
                passwordBox.PasswordChanged -= PasswordChanged;
            }

            if ((bool)e.NewValue)
            {
                passwordBox.PasswordChanged += PasswordChanged;
            }
        }

        private static void PasswordChanged(object sender, RoutedEventArgs e)
        {
            if (sender is PasswordBox passwordBox)
            {
                var boundPassword = GetBoundPassword(passwordBox);
                if (passwordBox.Password != boundPassword)
                {
                    SetBoundPassword(passwordBox, passwordBox.Password);
                }

            }
        }
    }
}