<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/04/30/determining-when-the-datefield-control-is-opened-or-closed-in-flex/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white" viewSourceURL="srcview/index.html">

    <mx:Script>
        <![CDATA[
            import mx.events.DropdownEvent;

            private function dateField_openClose(evt:DropdownEvent):void {
                arrColl.addItem(evt);
            }
        ]]>
    </mx:Script>

    <mx:ArrayCollection id="arrColl" />

    <mx:ApplicationControlBar dock="true">
        <mx:DateField id="dateField"
                open="dateField_openClose(event);"
                close="dateField_openClose(event);" />
    </mx:ApplicationControlBar>

    <mx:DataGrid id="dataGrid"
            dataProvider="{arrColl}"
            itemRenderer="mx.controls.Label"
            width="100%"
            height="100%" />

</mx:Application>