//-------------ACTIONS FOR CUSTOMER-------------------------
        //actions for adding new customer
        private void btnAddCustomer_Click(object sender, RoutedEventArgs e)
        {
            CustomerWin customerWindow = new CustomerWin();

            customerWindow.canvCustomerWindowMain.Visibility = Visibility.Hidden;
            customerWindow.canvNewCustomer.Visibility        = Visibility.Visible;
            customerWindow.Owner = this;
            customerWindow.ShowDialog();
        }
        private void openCustomer()
        {
            //this line will look for reference number part in the whole line on the list to put the correct details in customer's window
            string reference = Regex.Match(lstCustomers.SelectedItem.ToString(), @"\d+").Value;

            //creating new customer window and passing the reference to get all the correct details
            CustomerWin customerWin = new CustomerWin();

            //this method uses reference to fill in the new window with correct data
            customerWin.setCustomerWindow(reference);
            customerWin.canvNewCustomer.Visibility        = Visibility.Hidden;
            customerWin.canvCustomerWindowMain.Visibility = Visibility.Visible;
            customerWin.Owner = this;
            customerWin.ShowDialog();
        }