The function below shows how to sort the tree nodes.
function sortNodes(tree, parentNode){
	var t = $(tree);
	var data = t.tree('getData', parentNode.target);
	var nodes = $.extend(true, [], data.children||[]);
	$.map(nodes, function(node){
		t.tree('remove', node.target);
	});
	// sort the nodes
	nodes.sort(function(n1,n2){
		if (n1.text == n2.text){
			return 0;
		} else if (n1.text > n2.text){
			return 1;
		} else {
			return -1;
		}
	});
	// append the sorted nodes
	t.tree('append', {
		parent: parentNode.target,
		data: nodes
	});
}
Call the 'sortNodes' function to sort the children nodes of the selected node.
var t = $('#tt');	// the tree object
var selected = t.tree('getSelected');
if (selected){
	sortNodes(t, selected)
}