code: public void onChanged(ChangedEvent event) {
  		String value = (String) scaleItem.getValue();
  
  		Double scale = valueToScale.get(value);
  		if (scale != null && !Double.isNaN(pixelLength) && 0.0 != pixelLength) {
  			mapView.setCurrentScale(scale / pixelLength, MapView.ZoomOption.LEVEL_CLOSEST);
  		}
  	}
docs: When the user selects a different scale, have the map zoom to it.
  
  @see com.smartgwt.client.widgets.form.fields.events.ChangedHandler#onChanged
  (com.smartgwt.client.widgets.form.fields.events.ChangedEvent)