function rechtemaustaste (i) {
   if (!i) i = window.event;
   if ((i.type && i.type == "contextmenu") || (i.button && i.button == 2) || (i.which && i.which == 3)) {return false;}
 }
 if (document.layers) document.captureEvents(Event.MOUSEDOWN);
 document.onmousedown = rechtemaustaste;
 document.oncontextmenu = rechtemaustaste;