private void RadioButton_Click(object sender, RoutedEventArgs e)
        {
            string layerTypeTag = (string)((RadioButton)sender).Tag;

            OpenStreetMapLayer.TileServerList newTileServers;

            switch (layerTypeTag)
            {
            case "MapQuest":
                //Collection is replaced
                newTileServers = new OpenStreetMapLayer.TileServerList();
                newTileServers.Add("http://otile1.mqcdn.com/tiles/1.0.0/osm");
                newTileServers.Add("http://otile2.mqcdn.com/tiles/1.0.0/osm");
                newTileServers.Add("http://otile3.mqcdn.com/tiles/1.0.0/osm");
                osmLayer.TileServers = newTileServers;
                break;

            case "Cloudmade":
                //Collection is replaced
                newTileServers = new OpenStreetMapLayer.TileServerList();
                newTileServers.Add("http://a.tile.cloudmade.com/fd093e52f0965d46bb1c6c6281022199/3/256");
                newTileServers.Add("http://b.tile.cloudmade.com/fd093e52f0965d46bb1c6c6281022199/3/256");
                newTileServers.Add("http://c.tile.cloudmade.com/fd093e52f0965d46bb1c6c6281022199/3/256");
                osmLayer.TileServers = newTileServers;
                break;

            case "CycleMap":
                //same collection is pre-populated and hence needs to be refreshed.
                osmLayer.TileServers.Clear();
                osmLayer.TileServers.Add("http://a.tile.opencyclemap.org/cycle");
                osmLayer.TileServers.Add("http://b.tile.opencyclemap.org/cycle");
                osmLayer.TileServers.Add("http://c.tile.opencyclemap.org/cycle");
                osmLayer.Refresh();
                break;
            }
        }