private void BtnCover_OnClick(object sender, RoutedEventArgs e)
        {
            var win = SubWindow.Create("Cover Dialog");

            win.Show(WindowZOrder.Top);

            var coverWin = new CoverWindow
            {
                Owner      = win,
                Top        = win.Top,
                Left       = win.Left,
                Background = Brushes.Black,
                Title      = "CoverWindow" + SubWindow.GetOrder("Cover Dialog")
            };

            WindowsDockManager.SetDockBehavior(coverWin, new DockBehavior
            {
                Dock       = WinPosDockFlag.Full,
                RegionName = "CoverRegion",
                IsDockKeep = true
            });
            coverWin.SetDockOwner(win);
            coverWin.Show();
            coverWin.Hide();

            var coverWin1 = new CoverWindow
            {
                Owner      = win,
                Top        = win.Top,
                Left       = win.Left,
                Background = Brushes.Gray,
                Title      = "CoverWindow" + SubWindow.GetOrder("Cover Dialog") + "_1"
            };

            WindowsDockManager.SetDockBehavior(coverWin1, new DockBehavior
            {
                Dock       = WinPosDockFlag.Full,
                RegionName = "CoverRegion",
                IsDockKeep = true
            });
            coverWin1.SetDockOwner(win);
            coverWin1.Show();

            ShowMemorySize();
        }