Detecting whether an AIR application has run before

<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication 
	xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute"
		creationComplete="onCreationComplete()">
	
	<mx:Script>
		<![CDATA[
			private const FIRST_RUN_TOKEN_FILE:File = 
					File.applicationStorageDirectory.resolvePath("firstrun");
		
			private function onCreationComplete():void
			{
				if(FIRST_RUN_TOKEN_FILE.exists)
				{
					outputField.text = "This application HAS been run before";
				}
				else
				{
					var fs:FileStream = new FileStream();
						fs.open(FIRST_RUN_TOKEN_FILE, FileMode.WRITE);
						fs.close();
						
						outputField.text = "This application HAS NOT been run before";
				}
			}
			
			private function onResetClick():void
			{
				if(FIRST_RUN_TOKEN_FILE.exists)
				{
					FIRST_RUN_TOKEN_FILE.deleteFile();
				}
			}
		]]>
	</mx:Script>
	<mx:Text top="10" left="10" right="10" id="outputField" 
					textAlign="center" fontSize="20"/>
	<mx:Button label="Reset First Run Status" 
			id="resetButton" click="onResetClick()" 
				horizontalCenter="0" width="153" bottom="10"/>
	
</mx:WindowedApplication></pre>