private void addRecord_menuClick(object sender, RoutedEventArgs e)
        {
            var win = new AddEditRecord();

            win.customer = customer;
            win.ShowDialog();
        }
        private void editRecord_menuItem(object sender, RoutedEventArgs e)
        {
            if (list_records.SelectedIndex < 0)
            {
                return;
            }

            var win = new AddEditRecord();

            win.customer  = customer;
            win.operation = (Operation)list_records.SelectedItem;
            win._name     = win.operation.Name;
            win._date     = win.operation.Date;
            win.ShowDialog();
        }