final TabLayoutPanel tabs = new TabLayoutPanel(1.5, Unit.EM);
tabs.add(personalMap, "My Map");
tabs.add(friendsTab, "Friends");
tabs.setSize("100%", "100%");
tabs.addSelectionHandler(new SelectionHandler<Integer>() {
public void onSelection(SelectionEvent<Integer> event) {
Widget widget = tabs.getWidget(event.getSelectedItem());
if (widget instanceof RequiresResize) {
((RequiresResize) widget).onResize();
}