Styling the required indicator on a Spark FomItem container in Flex Hero

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/08/30/styling-the-required-indicator-on-a-spark-fomitem-container-in-flex-hero/ -->
<s:Application name="Spark_FormItem_requiredIndicatorSource_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/mx">
    <s:layout>
        <s:VerticalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <fx:Style>
        @namespace s "library://ns.adobe.com/flex/spark";
        @namespace mx "library://ns.adobe.com/flex/mx";
 
        s|FormItem {
            requiredIndicatorSource: "assets/asterisk_orange.png";
        }
    </fx:Style>
 
    <s:Form id="frm" defaultButton="{submitBtn}" backgroundColor="#EEEEEE">
        <s:FormHeading label="Spark Form Heading" backgroundColor="haloSilver" />
        <s:FormItem sequenceLabel="1." label="Username:" required="true">
            <s:helpContent>
                <s:Label text="user@domain.com" />
            </s:helpContent>
            <s:TextInput id="username" />
        </s:FormItem>
        <s:FormItem sequenceLabel="2." label="Password:" required="true">
            <s:helpContent>
                <s:Label text="weak" color="red" />
            </s:helpContent>
            <s:TextInput id="password1" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem sequenceLabel="3." label="Confirm password:">
            <s:helpContent>
                <s:HGroup>
                    <s:Label text="One" color="red" />
                    <s:Label text="Two" color="blue" />
                </s:HGroup>
            </s:helpContent>
            <s:TextInput id="password2" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem>
            <s:layout>
                <s:HorizontalLayout />
            </s:layout>
            <s:Button id="resetBtn" label="Reset" />
            <s:Button id="submitBtn" label="Submit" />
        </s:FormItem>
    </s:Form>
 
</s:Application>