if(window.addEventListener) {
          var eventType = (navigator.userAgent.indexOf('Firefox') !=-1) ? "DOMMouseScroll" : "mousewheel";
          window.addEventListener(eventType, handleMouseScroll, false);
}
function handleMouseScroll (event) {
            var app = document.getElementById("ViewerEnterpriseAnnotation");
            var edelta = (navigator.userAgent.indexOf('Firefox') !=-1) ? -event.detail : event.wheelDelta/40;                                   
            var o = {x: event.screenX, y: event.screenY, delta: edelta, ctrlKey: event.ctrlKey, altKey: event.altKey, shiftKey: event.shiftKey}
            app.handle MouseScroll (o);
}