var ie=Boolean(document.all);
    var ns4=Boolean(document.layers && !document.getElementById);
    var gecko=Boolean(!document.all && document.getElementById);
    
    function disableclick(e) {
        if (ns4) {
            if (e.which == 3) return false;
        } else if (gecko){
            if (e.button==2){
                e.cancelBubble=true;
                e.stopPropagation();
                e.preventDefault();
                return false;
            }
        }
    }
    if (ie) document.oncontextmenu=function() { return false; }
    else if (ns4){
        document.onmousedown=disableclick
        if (ns4) document.captureEvents(Event.MOUSEDOWN);
    } else {
        document.addEventListener('click',disableclick,false)
        document.addEventListener('dblclick',disableclick,false)
    }