document.oncontextmenu = function(){return false}
if(document.layers) {
    window.captureEvents(Event.MOUSEDOWN);
    window.onmousedown = function(e){
        if(e.target==document)return false;
    }
}
else {
    document.onmousedown = function(){return false}
}


<!--
var ns = (navigator.appName == "Netscape"); // true if the page is viewed in Netscape.

function rightClick( evnt )
{
 if (ns && ((evnt.which == 2) || (evnt.which == 3))) // check if it's Netscape and
                                                     // the mouse button is number 2 or 3.
  return false; // cancel the event-bubbling.
 else
  return true; // else, let all go on normally.
}

if (ns)
{
 window.captureEvents(Event.MOUSEDOWN);
 window.captureEvents(Event.MOUSEUP);
} // MOUSEDOWN and MOUSEUP events captured.

window.onmousedown = rightClick;
window.onmouseup = rightClick; // assign the rightClick function as the handler for those events.
//-->