code: public void onMapViewChanged(MapViewChangedEvent event) {
  		for (Layer<?> layer : layers) {
  			layer.updateShowing();
  
  			// If the map is resized quickly after a previous resize, tile requests are sent out, but when they come
  			// back, the world-to-pan matrix will have altered, and so the tiles are placed at the wrong positions....
  			// so we clear the store.
  			if (layer instanceof RasterLayer && event.isMapResized()) {
  				((RasterLayer) layer).getStore().clear();
  			}
  		}
  	}
docs: Update the visibility of the layers.
  
  @param event
  change event