Open Child Window in MVVM environment

namespace WindowWithMVVM
{
    using System.Windows.Controls;
    using System.Windows.Navigation;
    using WindowWithMVVM.Views;
    using System.Windows;

    /// <summary>
    /// Home page for the application.
    /// </summary>
    public partial class Home : Page
    {
        /// <summary>
        /// Creates a new <see cref="Home"/> instance.
        /// </summary>
        public Home()
        {
            InitializeComponent();

            this.Title = ApplicationStrings.HomePageTitle;
        }

        /// <summary>
        /// Executes when the user navigates to this page.
        /// </summary>
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
        }

        private void button1_Click(object sender, System.Windows.RoutedEventArgs e)
        {
            var window = new ChildWindow1 { DataContext = this.DataContext };
            window.Unloaded -= new System.Windows.RoutedEventHandler(ChildWindow_Unloaded);
            window.Unloaded += new System.Windows.RoutedEventHandler(ChildWindow_Unloaded);
            window.Show();
        }

        void ChildWindow_Unloaded(object sender, System.Windows.RoutedEventArgs e)
        {
            //You can do child window closing coding here like collect object, saving samething or changing status
            MessageBox.Show("Child window is closed now.");
        }
    }
}