//closes the window without making modifications
        private void btnCancel_Click(object sender, RoutedEventArgs e)
        {
            WindowEditCu customer = new WindowEditCu();

            customer.Show();
            this.Close();
        }
 //goes to the edit customer window, when a customer is double clicked in a data grid
 private void dgridCustomers_MouseDoubleClick(object sender, MouseButtonEventArgs e)
 {
     if (dgridCustomers.SelectedIndex != -1)
     {
         var currCust = dgridCustomers.SelectedItem as Customer;
         //stores the current customer's number for easy access in the edit window
         inst.CurrentCustomer = currCust.CustomerNo;
         WindowEditCu edit = new WindowEditCu();
         edit.Show();
         this.Close();
     }
 }