protected void onShow() {
super.onShow();
removeAll(true);
for (int i = 0; i < store.getCount(); i++) {
ModelData m = store.getAt(i);
CheckMenuItem item = new CheckMenuItem();
Object v = m.get(filter.getDisplayProperty());
item.setText(v == null ? "" : v.toString());
item.setChecked(selected.contains(m));
item.setHideOnClick(false);
item.setData("model", m);
item.addListener(Events.CheckChange, checkListener);