/// <summary>
    /// 窗体管理
    /// </summary>
    public class WindowManager
    {
        private static Lazy<WindowManager> manager = new Lazy<WindowManager>(() => new WindowManager());
        public static WindowManager Manager
        {
            get
            {
                return manager.Value;
            }
        }

        /// <summary>
        /// 存储所有加入的激活窗体
        /// </summary>
        private List<Window> lastWindows = new List<Window>();

        /// <summary>
        /// 将窗体添加到管理中
        /// </summary>
        /// <param name="window">要添加的窗体</param>
        public void AddActive(Window window)
        {
            //绑定窗体的激活事件
            window.Activated += Window_Activated;
            //绑定窗体的关闭事件
            window.Closing += Window_Closing;

            //如果添加的新窗体已加载,则添加到激活列表中
            if (window.IsLoaded)
                this.lastWindows.Add(window);
        }

        private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            this.RemoveActive(sender);
        }

        private Window RemoveActive(object sender)
        {
            var window = sender as Window;

            //关闭,则从队列中移除
            if (this.lastWindows.Contains(window))
            {
                this.lastWindows.Remove(window);
            }
            return window;
        }

        private void Window_Activated(object sender, EventArgs e)
        {
            var window = this.RemoveActive(sender);
            this.lastWindows.Add(window);
        }

        /// <summary>
        /// 关闭最后一个激活的窗体
        /// </summary>
        public void CloseActive()
        {
            //获取最后一个,直接关闭
            var window = this.lastWindows.LastOrDefault();
            if (window != null)
            {
                window.Close();
            }
        }

        /// <summary>
        /// 获取最后一个激活的窗体
        /// </summary>
        /// <returns></returns>
        public Window GetLastActive()
        {
            return this.lastWindows.LastOrDefault();
        }

        /// <summary>
        /// 关闭所有已激活的窗体
        /// </summary>
        public void CloseAll()
        {
            for (int i = this.lastWindows.Count - 1; i > -1; i--)
            {
                this.lastWindows[i].Close();
            }
        }
    }

  <StackPanel>
        <Button Content="Open" Click="Open_Click"/>
        <Button Content="Get" Click="Get_Click"/>
        <Button Content="Close" Click="Close_Click"/>
        <Button Content="Close All" Click="CloseAll_Click"/>

        <TextBox x:Name="txt"
                 TextWrapping="Wrap" Height="300" VerticalScrollBarVisibility="Auto" />

    </StackPanel>

  private void Open_Click(object sender, RoutedEventArgs e)
        {
           var window= new Window1(Guid.NewGuid().ToString());
            WindowManager.Manager.AddActive(window);
            window.Show();
        }

        private void Get_Click(object sender, RoutedEventArgs e)
        {
            var window = WindowManager.Manager.GetLastActive();
            if (window != null)
                this.txt.Text += window.Title + " :Active" + Environment.NewLine;
        }

        private void Close_Click(object sender, RoutedEventArgs e)
        {
            WindowManager.Manager.CloseActive();
        }

        private void CloseAll_Click(object sender, RoutedEventArgs e)
        {
            WindowManager.Manager.CloseAll();
        }

/// <summary>
    /// Window1.xaml 的交互逻辑
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1(string title)
        {
            InitializeComponent();
            this.Title = title;
        }

    }