tabSet.addTab(tab1);
tabSet.addTab(tab2);
tabSet.addTab(validatedTab);
tabSet.addTab(uneditableTab);
tabSet.addTabTitleChangedHandler(new TabTitleChangedHandler() {
@Override
public void onTabTitleChanged(TabTitleChangedEvent event) {
Tab tab = event.getTab();
if (tab.equals(validatedTab) && (event.getNewTitle() == null || !event.getNewTitle().substring(0, 4).equals("123-"))) {
SC.warn("Tab title must start with the prefix \"123-\"");