private void editCustomerBtn_Click(object sender, RoutedEventArgs e)
 {
     CustomerInfo customerToEdit = GetSelectedItem();
     if (customerToEdit != null)
     {
         ECMS.AddCustomer AddCustomerObj = new ECMS.AddCustomer(customerToEdit);
         AddCustomerObj.Show();
     }
 }
 private void addCustomerBtn_Click(object sender, RoutedEventArgs e)
 {
     ECMS.AddCustomer AddCustomerObj = new ECMS.AddCustomer(null);
     AddCustomerObj.Show();
 }