map.setSize("300px", "300px");
RootPanel.get().add(map);
final Marker marker = new Marker(atlanta);
map.addOverlay(marker);
marker.addMarkerVisibilityChangedHandler(new MarkerVisibilityChangedHandler() {
public void onVisibilityChanged(MarkerVisibilityChangedEvent event) {
assertEquals(event.getSender(), marker);
assertFalse(event.isVisible());
finishTest();
}