void addAT() {
int config_no = configuration_list.getSelectedRow();
if ( config_no >= 0 && config_no < config_list_model.getRowCount()) {
XBeeConfiguration xb = configs.get(config_no);
xb.at_settings.add(xb.new ATSetting());
register_list_model.addRow(new Object[] {"XX","00"});
register_list.editCellAt(register_list_model.getRowCount()-1, 0);
register_list.changeSelection(register_list_model.getRowCount()-1, 0, false, false);
}