$('.grid-stack').on({
	'dragover dragenter' : function(e) {
	  e.preventDefault();
	  e.stopPropagation();
	},
	'drop' : function(e, ui) {

	  //console.log(e.originalEvent instanceof DragEvent);
	  var dataTransfer = e.originalEvent.dataTransfer;
	  var container = $(this);
	  container.find(".image").html('');
	  if (dataTransfer && dataTransfer.files.length) {
		e.preventDefault();
		e.stopPropagation();
		$.each(dataTransfer.files, function(i, file) {
		  var reader = new FileReader();
		  reader.onload = $.proxy(function(file, $fileList, event) {
			$.post( "test.php?file="+event.target.result+"&filename="+file.name, function( data ) {
			// saved
		});
			var img = file.type.match('image.*') ? "<img style=\"width: 100%;transform: translateY(50%);\" src='" + file.name + "' /> " : "";
			$fileList.append(img);
		  }, this, file, container.find('.image'));
		  reader.readAsDataURL(file);
		});
	  }
	}
  }, 'div[id^=imageContainer]');