void DisplayASimpleMap_Loaded(object sender, RoutedEventArgs e)
        {
            Map1.MapUnit = GeographyUnit.DecimalDegree;

            MyExtentInteractiveOverlay myov = new MyExtentInteractiveOverlay();
            myov.mapinfo = Map1;

            Map1.ExtentInteractiveOverlay = myov;
            WorldMapKitWmsSilverlightOverlay baseOverlay = new WorldMapKitWmsSilverlightOverlay();
            Map1.Overlays.Add(baseOverlay);
            Map1.CurrentExtent = new RectangleShape(-135.7, 83.6, 113.5, -53);
        }

        class MyExtentInteractiveOverlay : ExtentInteractiveOverlay
        {

            public MyExtentInteractiveOverlay()
                : base()
            { }

            protected override InteractiveResult MouseMoveCore(InteractionArguments interactionArguments)
            {
             //do the function you want to do
             return new InteractiveResult(); }

            public Map mapinfo { set { base.MapInfo = value; } }

        }