public void addMapZoomListener(final MapZoomListener listener) {
if (zoomListeners == null) {
zoomListeners = new ListenerCollection<MapZoomListener>();
}
JavaScriptObject zoomEventHandles[] = {EventImpl.impl.addListener(jsoPeer,
MapEvent.ZOOMEND, new IntIntCallback() {
@Override
public void callback(int oldLevel, int newLevel) {
listener.onZoom(MapWidget.this, oldLevel, newLevel);
}
})};