/// <summary>
        /// Method to import a text file and generate list view row
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnImport_Click(object sender, RoutedEventArgs e)
        {
            string fileName;            // local variable

            OpenFileDialog openFileDialog1 = new OpenFileDialog();

            openFileDialog1.Filter = "Text documents (.txt)|*.txt";             // Filter files by extension
            Nullable <bool> result = openFileDialog1.ShowDialog();

            try
            {
                if (result == true)                      //Dialog box to open the xml file
                {
                    fileName = openFileDialog1.FileName; //retrieve filename and path

                    Invoice newInvoice = new Invoice();  //initiate object

                    InvoiceReader newDocument = new InvoiceReader(fileName, newInvoice);

                    newDocument.ReadInvoice();

                    newInvoice.NumberOfItems = newDocument.TotalNumberItems();

                    lstInvoices.Items.Add(new MyItem {
                        ID = newInvoice.InvoiceNumber.ToString(), Company = newInvoice.CompanyDebtorName, NumberOfItems = newInvoice.NumberOfItems.ToString(), ContactPerson = newInvoice.DebtorContactPerson, DueDate = newInvoice.DueDate.ToString("yyyy-MM-dd"), TotalAmount = newInvoice.TotalInvoice().ToString("F")
                    });

                    lstInvoices.ScrollIntoView(lstInvoices.Items[lstInvoices.Items.Count - 1]);

                    addInvoiceToLibrary.AddElement(newInvoice);
                }
            }
            catch (Exception error)
            {
                MessageBox.Show(error.Message + "Environment.NewLine" + error.StackTrace, "Error");
            }
            finally
            {
            }
        }