/// <summary>
        /// Uses OpenXml to read sheet names, extremely fast,
        /// the vb.net xml example is just as fast.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void cmdGetSheetNamesXml_Click(object sender, EventArgs e)
        {
            var helper     = new OpenXmlExamples();
            var fileName   = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Customers.xlsx");
            var sheetNames = helper.SheetNames(fileName);

            if (helper.IsSuccessFul)
            {
                sheetNames.Insert(0, "Select sheet");
                cboGetSheetNamesXml.DataSource = sheetNames;
            }
            else
            {
                Dialogs.ExceptionDialog(helper.LastException);
            }
        }
        /// <summary>
        /// Setup
        /// * Get fresh copies of Excel files.
        /// * Get sheet names from Customers.xlsx via OpenXml
        /// * Setup a timer to watch for Excel processes open.
        ///   This assumes you don't have Excel open outside this app.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Form1_Shown(object sender, EventArgs e)
        {
            timerForExcel.Enabled = true;

            /*
             * Start with a clean slate in regards to base Excel files
             */
            _fileOperations.RemoveExcelFiles();

            /*
             * These files were not copied over
             */
            _fileOperations.RemoveOtherExcelFiles(new[]
            {
                "Cust.xlsx",
                "PeopleDemo.xlsx",
                "BadPeopleDemo.xlsx",
                "Customers.xml"
            });

            /*
             * Copy files from base file folder
             */
            _fileOperations.CopyExcelFiles();

            if (_fileOperations.HasException)
            {
                MessageBox.Show($"Issues with file delete/copy{Environment.NewLine}{_fileOperations.LastExceptionMessage}");
            }

            var fileName = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Customers.xlsx");

            /*
             * There is also an automated method that does the
             * same as this in ExcelBase class. This method was
             * used as it's faster than using automation.
             */
            var helper     = new OpenXmlExamples();
            var sheetNames = helper.SheetNames(fileName);

            sheetNames.Insert(0, "Select sheet");
            cboCustomerSheetNames.DataSource = sheetNames;
        }