private void Form1_Load(object sender, EventArgs e)
        {
            winformsMap1.MapUnit = GeographyUnit.Meter;
            winformsMap1.ZoomLevelSet = new ThinkGeoCloudMapsZoomLevelSet();

            // Please input your ThinkGeo Cloud Client ID / Client Secret to enable the background map. 
            cloud = new ThinkGeoCloudRasterMapsOverlay("ThinkGeo Cloud Client ID", "ThinkGeo Cloud Client Secret");
            cloud.TileCache = null;

            cloud.Drawing += ThinkGeoCloudMapsOverlay_Drawing;
            cloud.Drawn += ThinkGeoCloudMapsOverlay_Drawn;
            cloud.SendingWebRequest += Cloud_SendingWebRequest;

            OpenStreetMapOverlay osm = new OpenStreetMapOverlay();
            osm.SendingWebRequest += Osm_SendingWebRequest;
            osm.Drawing += Osm_Drawing;
            osm.Drawn += Osm_Drawn;

            osm.TileCache = null;

            winformsMap1.Overlays.Add(osm);

            winformsMap1.CurrentExtent = new ThinkGeo.MapSuite.Shapes.RectangleShape(-8663887.6887665, 4766503.70586541, -8492821.62041464, 4652765.40840895);
            winformsMap1.Refresh();
        }

        private void Cloud_SendingWebRequest(object sender, SendingWebRequestEventArgs e)
        {
            Debug.WriteLine(e.WebRequest.RequestUri.ToString());
        }

        private void Osm_Drawn(object sender, DrawnOverlayEventArgs e)
        {
            Debug.WriteLine("Drawn" + DateTime.Now.ToShortTimeString());
        }

        private void Osm_Drawing(object sender, DrawingOverlayEventArgs e)
        {
            Debug.WriteLine("Drawing" + DateTime.Now.ToShortTimeString());
        }

        private void Osm_SendingWebRequest(object sender, SendingWebRequestEventArgs e)
        {
            (e.WebRequest as HttpWebRequest).UserAgent = "Test APP";
            Debug.WriteLine(e.WebRequest.RequestUri.ToString());
        }

        private void ThinkGeoCloudMapsOverlay_Drawn(object sender, DrawnOverlayEventArgs e)
        {
            Debug.WriteLine("Drawn" + DateTime.Now.ToShortTimeString());
        }

        private void ThinkGeoCloudMapsOverlay_Drawing(object sender, DrawingOverlayEventArgs e)
        {
            Debug.WriteLine("Drawing" + DateTime.Now.ToShortTimeString());
        }