jQuery UI Sortable Droponempty

<link rel="stylesheet" href="http://code.jquery.com/ui/1.9.2/themes/base/jquery-ui.css" />
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script type="text/javascript" src="http://code.jquery.com/ui/1.9.2/jquery-ui.js"></script>
<script type="text/javascript" src="http://www.pureexample.com/js/lib/jquery.ui.touch-punch.min.js"></script>


<!-- CSS -->
<style type="text/css">
.list {
    background-color: lightblue;
    border: 1px solid gray;
}

.items .ui-selected {
    background: red;
    color: white;
    font-weight: bold;
}

.items {
    list-style-type: none;
    margin-left: 10px;
    padding: 0;
    width: 100px;
    float: left;
}

.items li {
    margin: 2px;
    padding: 2px;
    cursor: pointer;
    border-radius: 3px;
}

.g {
    background-color: lightgreen;
}

.o {
    background-color: orange;
}

.highlight {
    border: 2px solid red;
    font-weight: bold;
}
</style>


<!-- Javascript -->
<script>
$(function () {
	$("#items1,#items2,#items4").sortable({
		connectWith: "#items4",
		dropOnEmpty: true
	});

	$("#items3").sortable({
		connectWith: "#items4",
		dropOnEmpty: false
	});

	$("#items1,#items2,#items3,#items4").disableSelection();
});
</script>

<!-- HTML -->
<ul id="items1" class="items" style="font-size:14px;">
    <li class="list">Drop on empty</li>
    <li class="list">Drop on empty</li>
    <li class="list">Drop on empty</li>
    <li class="list">Drop on empty</li>
    <li class="list">Drop on empty</li>    
</ul>
<ul id="items2" class="items" style="font-size:14px;">
    <li class="list g">Drop on empty</li>
    <li class="list g">Drop on empty</li>
    <li class="list g">Drop on empty</li>
    <li class="list g">Drop on empty</li>
    <li class="list g">Drop on empty</li>    
</ul>
<ul id="items3" class="items" style="font-size:14px;">
    <li class="list o">No drop on empty</li>
    <li class="list o">No drop on empty</li>
    <li class="list o">No drop on empty</li>
    <li class="list o">No drop on empty</li>
    <li class="list o">No drop on empty</li>    
</ul>
<ul id="items4" class="items" style="border:1px dotted #A3A3A3;height:160px;background-color:#D6E5FF" title="Empty Placeholder">
</ul>