var Mac = navigator.userAgent.indexOf("Mac") != -1   ? true : false;
function mdown(e) {
if (navigator.appName == "Microsoft Internet Explorer") {
if (event.button == 2 || (Mac && (event.ctrlKey || event.keyCode == 91))) {
return(false);
}
} else if (navigator.appName == "Netscape") {
if (e.which == 3 || e.modifiers == 2 || e.ctrlKey) {
return false;
}
} 
}
function noclick(){
return false;
}
document.oncontextmenu = noclick;
if (document.all && (Mac || ! document.getElementById)) {
document.onmousedown = mdown;
document.onkeydown = mdown;
} else if (document.layers) {
window.captureEvents(Event.MOUSEDOWN | Event.modifiers | Event.KEYDOWN);
window.onmousedown = mdown;
window.onkeydown = mdown;
} else if(navigator.userAgent.indexOf("Netscape6")!=-1){
document.onmouseup = mdown; 
document.onkeydown = mdown;
}