<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/06/06/changing-the-label-text-alignment-in-a-formitem-container-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Script>
        <![CDATA[
            import mx.events.ListEvent;
 
            private function comboBox_change(evt:ListEvent):void {
                var cssObj:CSSStyleDeclaration = StyleManager.getStyleDeclaration(".customTextAlignLabel");
                cssObj.setStyle("textAlign", evt.currentTarget.selectedItem);
            }
        ]]>
    </mx:Script>
 
    <mx:Style>
        FormItem {
            labelStyleName: customTextAlignLabel;
        }
 
        .customTextAlignLabel {
            textAlign: left;
        }
    </mx:Style>
 
    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="textAlign:">
                <mx:ComboBox id="comboBox"
                        dataProvider="[left,center,right]"
                        change="comboBox_change(event);" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>
 
    <mx:TitleWindow>
        <mx:Form>
            <mx:FormItem label="Button">
                <mx:TextInput />
            </mx:FormItem>
            <mx:FormItem label="ButtonBar">
                <mx:TextInput />
            </mx:FormItem>
            <mx:FormItem label="CheckBox">
                <mx:TextInput />
            </mx:FormItem>
            <mx:FormItem label="ColorPicker">
                <mx:TextInput />
            </mx:FormItem>
            <mx:FormItem label="ComboBox">
                <mx:TextInput />
            </mx:FormItem>
        </mx:Form>
    </mx:TitleWindow>
 
</mx:Application>