private void button2_Click(object sender, RoutedEventArgs e)
        {
            ClosableTab theTabItem = new ClosableTab();

            theTabItem.Title = "A much longer title for an example";
            tabControl1.Items.Add(theTabItem);
            theTabItem.Focus();
        }
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            ClosableTab theTabItem = new ClosableTab();

            theTabItem.Title = "Small title";
            tabControl1.Items.Add(theTabItem);
            theTabItem.Focus();
        }
        private void button3_Click(object sender, RoutedEventArgs e)
        {
            Assembly assem;

            assem = Assembly.LoadFile($"{Directory.GetCurrentDirectory()}\\WpfDemo.exe");
            var onePage = assem.CreateInstance("WpfDemo.SingleSelectors.SingleSelector");

            ClosableTab theTabItem = new ClosableTab();

            theTabItem.Content = onePage;
            theTabItem.Title   = "Single Selector";
            tabControl1.Items.Add(theTabItem);
            theTabItem.Focus();
        }