Zoom in and zoom out does not work in windowless mode

Here, you can try something like this to push the mouse wheel events through for those browsers:

Add this javascript to the page (Make sure the changes don't conflict with other javascript you have):

        function reactToScroll(delta) {
            slPlugin.Content.scrollHelper.SendScrollEvent(delta);
        }

        function mouseScroll(event) {
            var delta = 0;
            if (event.wheelDelta) {
                delta = event.wheelDelta / 120;
            }
            if (event.detail) {
                delta = -event.detail / 3;
            }
            if (delta != 0) {
                reactToScroll(delta);
            }
        }

        window.onload = init;
        var slPlugin;
        function init() {
            slPlugin = document.getElementById('mapHost');
            if (slPlugin != null) {
                if (slPlugin.addEventListener) {
                    slPlugin.addEventListener('DOMMouseScroll', mouseScroll, true);
                    slPlugin.addEventListener('mousewheel', mouseScroll, true);
                }
            }
        }

Make sure to find the object tag for your Silverlight control on the page and add
id="mapHost" to it.

Then, in the code behind for your silverlight page (presumably you will have other logic in your silverlight page, so merge this in carefully):

    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();

            HtmlPage.RegisterScriptableObject("scrollHelper", new ScrollHelper(this));
        }
    }

    public class ScrollHelper
    {
        private MainPage _owner;
        public ScrollHelper(MainPage owner)
        {
            _owner = owner;
        }

        [ScriptableMember()]
        public void SendScrollEvent(double scrollChange)
        {
            double currzoom = _owner.theMap.WindowZoom;
            currzoom += scrollChange;
            if (currzoom < 0)
            {
                currzoom = 0;
            }
            _owner.theMap.WindowZoom = currzoom;
        }
    }