Navigating to the parent directory on a FileSystemDataGrid control in Adobe AIR

<?xml version="1.0" encoding="utf-8"?>
<!--  -->
<mx:WindowedApplication name="FileSystemDataGrid_navigateUp_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
 
    <mx:Script>
        <![CDATA[
            import mx.events.FileEvent;
 
            private function btn_click(evt:MouseEvent):void {
                dataGrid.navigateUp();
            }
 
            private function dataGrid_directoryChange(evt:FileEvent):void {
                application.status = evt.file.nativePath;
            }
        ]]>
    </mx:Script>
 
    <mx:ApplicationControlBar dock="true">
        <mx:Button id="btn"
                label="navigateUp()"
                click="btn_click(event);" />
    </mx:ApplicationControlBar>
 
    <mx:FileSystemDataGrid id="dataGrid"
            directoryChange="dataGrid_directoryChange(event);"
            width="100%"
            height="100%" />
 
</mx:WindowedApplication>