Disabling the context menu on long taps on Android

The context menu has its own event. You just need to catch it and stop it from propagating.

window.oncontextmenu = function(event) {
     event.preventDefault();
     event.stopPropagation();
     return false;
};

That can be done using CSS:

img {
  pointer-events: none;
}

This should work on 1.6 or later (if I recall correctly). I don't believe there's a workaround for 1.5 or earlier.

<!DOCTYPE html>
<html>
<head>
  <script>
    function absorbEvent_(event) {
      var e = event || window.event;
      e.preventDefault && e.preventDefault();
      e.stopPropagation && e.stopPropagation();
      e.cancelBubble = true;
      e.returnValue = false;
      return false;
    }

    function preventLongPressMenu(node) {
      node.ontouchstart = absorbEvent_;
      node.ontouchmove = absorbEvent_;
      node.ontouchend = absorbEvent_;
      node.ontouchcancel = absorbEvent_;
    }

    function init() {
      preventLongPressMenu(document.getElementById('theimage'));
    }
  </script>
</head>
<body onload="init()">
  <img id="theimage" src="http://www.google.com/logos/arthurboyd2010-hp.jpg" width="400">
</body>
</html>