<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/08/18/setting-the-button-label-placement-on-a-radiobutton-control-in-flex/ -->
<mx:Application name="RadioButton_labelPlacement_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            import mx.controls.ButtonLabelPlacement;
            import mx.events.ListEvent;

            private const arr:Array = [ButtonLabelPlacement.LEFT,
                                        ButtonLabelPlacement.RIGHT,
                                        ButtonLabelPlacement.TOP,
                                        ButtonLabelPlacement.BOTTOM];

            private function comboBox_change(evt:ListEvent):void {
                var value:String = comboBox.selectedItem.toString();
                radioButton.labelPlacement = value;
            }
        ]]>
    </mx:Script>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="labelPlacement:">
                <mx:ComboBox id="comboBox"
                        dataProvider="{arr}"
                        selectedIndex="1"
                        change="comboBox_change(event);" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:RadioButton id="radioButton"
            label="RadioButton" />

</mx:Application>