function addEvent(obj, evType, fn){
        if (obj.addEventListener){
            obj.addEventListener(evType, fn, true);
            return true;
        } else if (obj.attachEvent) {
            var r = obj.attachEvent('on'+evType, fn);
            return r;
        } else {
            return false;
        }
    }
//    addEvent(window, 'load', function() {
//        hide_on_load();
//        show_on_load();
//    });
    
    function hide_on_load() {
        var elements_hide = document.getElementsByClassName('hide_on_load');
        if (!elements_hide) { return; }
        for(var x=0; x<elements_hide.length; x++) {
            elements_hide[x].style.display = "none";
        }
    }
    
    function show_on_load() {
        var elements_show = document.getElementsByClassName('show_on_load');
        if (!elements_show) { return; }
        for(var x=0; x<elements_show.length; x++) {
            elements_show[x].style.display = "block";
        }
    }