<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/09/30/setting-the-button-height-on-a-buttonbar-control-in-flex/ -->
<mx:Application name="ButtonBar_buttonHeight_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Style>
        ButtonBar {
            buttonHeight: 16;
            buttonStyleName: buttonBarButtonStyles;
        }
    
        .buttonBarButtonStyles {
            textAlign: left;
        }
    </mx:Style>

    <mx:Array id="arr">
        <mx:Object label="Red"
                icon="@Embed('assets/bullet_red.png')" />
        <mx:Object label="Orange"
                icon="@Embed('assets/bullet_orange.png')" />
        <mx:Object label="Yellow"
                icon="@Embed('assets/bullet_yellow.png')" />
        <mx:Object label="Green"
                icon="@Embed('assets/bullet_green.png')" />
        <mx:Object label="Blue"
                icon="@Embed('assets/bullet_blue.png')" />
    </mx:Array>

    <mx:ApplicationControlBar dock="true">
        <mx:Form styleName="plain">
            <mx:FormItem label="direction:">
                <mx:ComboBox id="comboBox"
                        dataProvider="[horizontal,vertical]" />
            </mx:FormItem>
        </mx:Form>
    </mx:ApplicationControlBar>

    <mx:ButtonBar id="buttonBar"
            dataProvider="{arr}"
            direction="{comboBox.selectedItem}" />

</mx:Application>