Prevent droppable from accepting when it is overlaid by another element in jqueryUI?

Question

I've positioned 2 containers such a way that container one overlays on another. But when I drop an item onto the container one, the dropped item goes into both containers. How do I restrict that?

   //JS Code: 
   $("div.draggable").draggable({
      helper: "clone",
      cursor: "move",
      containment: 'body'
    });


    $("div.droppable").droppable({
      addClasses: false,
      drop: function (event, ui) {
        var $draggable = $(ui.draggable),
            $droppable = $(this);

        $droppable.html($draggable.clone());
      }
    });

Demo: http://jsfiddle.net/HL8VR/

Answer 1

Thanks @Nal but nothing works for me, So I Created this hack.

I store some data with an element once an item is dropped onto it. Unfortunately the data is stored with both Droppables which I could not isolate.

$("div.droppable").droppable({
  addClasses: false,
  drop: function (event, ui) {
    var $draggable = $(ui.draggable),
        $droppable = $(this);

    $droppable.data({'drop': true, 'draggable': $draggable});
  }
});

But once the item is dropped, I could figure out which droppable I'm hovering on.

$('div.droppable').hover(function() {
    if ($(this).data('drop') === true) {
        $(this).html($($(this).data('draggable')).clone());

        // Clears the data from both droppables to avoid duplicating the item in them
        $('div.droppable').data({'drop': false, 'draggable': false});
    }        
});

Demo: http://jsfiddle.net/codef0rmer/AVQVs/