private void btnMultipleFeatures_Click(object sender, RoutedEventArgs e)
        {
            Collection <string> featureIDs = new Collection <string>();

            featureIDs.Add("63");  // For US
            featureIDs.Add("6");   // For Canada
            featureIDs.Add("137"); // For Mexico

            FeatureLayer worldLayer = mapView.FindFeatureLayer("WorldLayer");

            lock (worldLayer)
            {
                if (!worldLayer.IsOpen)
                {
                    worldLayer.Open();
                }
                Collection <Feature> features = worldLayer.FeatureSource.GetFeaturesByIds(featureIDs, new string[0]);
                mapView.CurrentExtent = MapUtil.GetBoundingBoxOfItems(features);
            }

            mapView.Refresh();
        }