//define 3 different overlays, add them into the Map1.CustomOverlays with the specified sequence.
                LayerOverlay areaOverlay = new LayerOverlay();
                LayerOverlay lineOverlay = new LayerOverlay();
                LayerOverlay pointOverlay = new LayerOverlay();

                Map1.CustomOverlays.Add(pointOverlay);
                Map1.CustomOverlays.Add(lineOverlay);
                Map1.CustomOverlays.Add(areaOverlay);


                //when adding shape file layers dynamically, add them to the relative overlays depending on the shape file type.
                ShapeFileFeatureLayer layer = new ShapeFileFeatureLayer();
                layer.Open();
                ShapeFileType type = layer.GetShapeFileType();

                if (type == ShapeFileType.Multipoint || type == ShapeFileType.MultipointM || type == ShapeFileType.MultipointZ || type == ShapeFileType.Point || type == ShapeFileType.PointM || type == ShapeFileType.PointZ)
                {
                    pointOverlay.Layers.Add(layer);
                }
                //
                // else line
                // else polygon



                //OnMapClick
                foreach (LayerOverlay overlay in Map1.CustomOverlays)
                {
                    foreach (ShapeFileFeatureLayer item in overlay.Layers)
                    {
                        Collection<Feature> features = item.QueryTools.GetFeaturesIntersecting(mousePoint, ReturningColumnsType.AllColumns);

                        if (features.Count > 0)
                        { 
                            //the features are what you want.
                        }
                    }
                }