// Internet Explorer:
if (document.all)
  document.onselectstart =
    function () { return false; };

// Netscape 4:
if (document.layers) {
  document.captureEvents(Event.MOUSEDOWN);
  document.onmousedown =
    function (evt) { return false; };
}

// Netscape 6:
document.onmousedown = function () { return false; };