<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/07/27/setting-the-border-thickness-on-a-datechooser-control-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Style>
        DateChooser {
            borderThickness: 5;
        }
    </mx:Style>

    <mx:DateChooser id="dateChooser" />

</mx:Application>