private void button_Click(object sender, System.Windows.RoutedEventArgs e)
        {
            if (SelectedEmployee != null)
            {
                SelectedTicket.SetEmployeeId(SelectedEmployee.Id);
                SelectedTicket.Update();
            }
            Window window1 = Window.GetWindow(this);

            if (window1 != null)
            {
                window1.Close();
            }
        }