private void btnSave_Click(object sender, EventArgs e)
        {

            try
            {
                using (StreamWriter myWriter = new StreamWriter(diskFile, false))   //false means do not append data!

                    foreach (string myItem in lstItems.Items)
                    {
                        myWriter.WriteLine(myItem);
                    }
                MessageBox.Show("Your data has been updated.",
                    "System message", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }

            catch (Exception ex)
            {
                MessageBox.Show("I could not save your changes." + ex.Message,
                    "System Message", MessageBoxButtons.OK, MessageBoxIcon.Error);

            }
            
        }