final TableColumn def = columnModel.getColumn(i);
final CheckMenuItem check = new CheckMenuItem();
check.setHideOnClick(false);
check.setText(def.getText());
check.setChecked(!def.isHidden());
check.addSelectionListener(new SelectionListener<MenuEvent>() {
public void componentSelected(MenuEvent ce) {
def.setHidden(!check.isChecked());
showColumn(def.index, !def.isHidden());