private void BtnShowView_Click(object sender, RoutedEventArgs e)
        {
            switch (((ComboBoxItem)cbViews.SelectedItem).Tag)
            {
            case "View1":
                View1 view1 = new View1();
                view1.Show();
                break;

            case "View2":
                View2 view2 = new View2(false);
                view2.Show();
                break;

            case "View3":
                View3 view3 = new View3();
                view3.Show();
                break;

            case "ucDemo":
            case "ucDemo2":
                MessageBox.Show("Los user controls no pueden salir en ventanas");
                break;
            }
        }