Displaying scroll tips in a List control in Flex

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/03/28/displaying-scroll-tips-in-a-list-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.controls.scrollClasses.ScrollBarDirection;
            import mx.utils.StringUtil;

            private function list_scrollTipFunc(dir:String, pos:Number):String {
                var pct:Number = pos / list.maxVerticalScrollPosition;
                return StringUtil.substitute("{0} / {1} ({2}%)",
                        pos, // current
                        list.maxVerticalScrollPosition, // max
                        numberFormatter.format(pct * 100) // percent
                    );
            }
        ]]>
    </mx:Script>

    <mx:NumberFormatter id="numberFormatter" precision="0" />

    <mx:Array id="arr">
        <mx:Object label="Accordion" />
        <mx:Object label="ApplicationControlBar" />
        <mx:Object label="Box" />
        <mx:Object label="Canvas" />
        <mx:Object label="ControlBar" />
        <mx:Object label="DividedBox" />
        <mx:Object label="Form" />
        <mx:Object label="FormHeading" />
        <mx:Object label="FormItem" />
        <mx:Object label="Grid" />
        <mx:Object label="HBox" />
        <mx:Object label="HDividedBox" />
        <mx:Object label="Panel" />
        <mx:Object label="TabNavigator" />
        <mx:Object label="Tile" />
        <mx:Object label="TitleWindow" />
        <mx:Object label="VBox" />
        <mx:Object label="VDividedBox" />
        <mx:Object label="ViewStack" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:CheckBox id="checkBox"
                label="showScrollTips:"
                labelPlacement="left"
                selected="true" />
    </mx:ApplicationControlBar>

    <mx:List id="list"
            dataProvider="{arr}"
            rowCount="6"
            showScrollTips="{checkBox.selected}"
            scrollTipFunction="list_scrollTipFunc"
            verticalScrollPolicy="on" />

</mx:Application>