I have a different behavior for the -webkit-grabbing css parameter for cursor on Safari. It works only on <button element, not <div>:
.a {
  background-color: green;
  width: 200px;
  height: 200px;
 }
.b {
  background-color: yellow;
  width: 200px;
  height: 200px;
 }
.grab {
  cursor: grab;
  cursor: -moz-grab;
  cursor: -webkit-grab;
}
.grab:active {
  cursor: grabbing;
  cursor: -moz-grabbing;
  cursor: -webkit-grabbing;
}<html>
<body>
<div class='a grab'>
</div>
<button class='b grab'>
</button>
</body>
</html>For Chrome and Firefox it works as espected.
 
    