<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/01/11/displaying-the-number-of-children-in-each-branch-of-a-flex-tree-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            private function tree_labelFunc(item:XML):String {
                var label:String = item.@label;
                if (tree.dataDescriptor.hasChildren(item)) {
                    label += " (" + tree.dataDescriptor.getChildren(item).length + ")";
                }
                return label;
            }
        ]]>
    </mx:Script>

    <mx:XML id="treeDP">
        <root>
            <node label="i) One" />
            <node label="i) Two" />
            <node label="i) Three" />
            <node label="i) Four">
                <node label="ii) One" />
                <node label="ii) Two" />
                <node label="ii) Three">
                    <node label="iii) One" />
                    <node label="iii) Two" />
                </node>
                <node label="ii) Four" />
            </node>
            <node label="1. Five" />
            <node label="1. Six" />
        </root>
    </mx:XML>

    <mx:Tree id="tree"
            dataProvider="{treeDP}"
            labelFunction="tree_labelFunc"
            showRoot="false"
            width="200" />

</mx:Application>