code: private void initialize() {
  		registrations.clear();
  		for (Layer<?> layer : mapModel.getLayers()) {
  			registrations.add(layer.addLayerChangedHandler(new LayerChangedHandler() {
  
  				public void onLabelChange(LayerLabeledEvent event) {
  				}
  
  				public void onVisibleChange(LayerShownEvent event) {
  					render();
  				}
  
  			}));
  			registrations.add(layer.addLayerStyleChangedHandler(new LayerStyleChangedHandler() {
  
  				public void onLayerStyleChange(LayerStyleChangeEvent event) {
  					render();
  				}
  			}));
  		}
  		for (final VectorLayer layer : mapModel.getVectorLayers()) {
  			layer.addLayerFilteredHandler(new LayerFilteredHandler() {
  
  				public void onFilterChange(LayerFilteredEvent event) {
  					render();
  				}
  			});
  		}
  		render();
  	}
docs: Called when the MapModel configuration has been loaded.