function clickIE() {
      if (document.all) {      
        return false;
        }
      }
    function clickNS(e) {
      if (document.layers||(document.getElementById&&!document.all)) {
        if (e.which==2||e.which==3) {       
          return false;
        }
      }
    }
    if (document.layers){
      document.captureEvents(Event.MOUSEDOWN);
      document.onmousedown=clickNS;
    } else {
      document.onmouseup=clickNS;
      document.oncontextmenu=clickIE;
      }