dojo.addOnLoad(
    function(){ 
        dojo.query(".menuitem img").forEach(function(node, index){
            dojo.connect(node,"onmouseenter",onMenuItemMouseEnter);
            dojo.connect(node,"onmouseleave",onMenuItemMouseLeave);
            var src = node.src;
            dojo.attr(node,"src_off",src);
            src = src.substr(0,src.lastIndexOf("."))+".hover.gif";
            dojo.attr(node,"src_on",src);
        });
    }
);

function onMenuItemMouseEnter(/* Event */ event) {
    dojo.stopEvent(event);
    var img = event.currentTarget;
    var src = dojo.attr(img,"src_on");
    img.src = src;
    dojo.query(".submenu").style("display","none");
    var id = img.parentNode.id;
    var id = id.substr(0,id.lastIndexOf("_"))+"_submenu";
    var submenu = dojo.byId(id);
    if (submenu) {
       dojo.style(dojo.byId(id),"display","block");
    }
}

function onMenuItemMouseLeave(/* Event */ event) {
    dojo.stopEvent(event);
    var img = event.currentTarget;
    var src = dojo.attr(img,"src_off");
    img.src = src;
}