<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" creationComplete="oninit()">
	<mx:states>
		<mx:State name="aa">
			<mx:AddChild position="lastChild">
				<mx:TabNavigator x="121" y="71" width="200" height="200" id="tabnabigator" creationPolicy="all">
					<mx:Canvas label="タブ 1" width="100%" height="100%">
					</mx:Canvas>
					<mx:Canvas label="a" width="100%" height="100%">
					</mx:Canvas>
					<mx:Canvas label="v" width="100%" height="100%">
					</mx:Canvas>
				</mx:TabNavigator>
			</mx:AddChild>
		</mx:State>
	</mx:states>

	<mx:Script>
		<![CDATA[
			import mx.events.IndexChangedEvent;
			private function oninit():void
			{
				tabnabigator.addEventListener(IndexChangedEvent.CHANGE, abc);
			}
			private function abc(e:Event):void {
				trace("changed");
			}
		]]>
	</mx:Script>
</mx:Application>

tabnabigator.addEventListener(IndexChangedEvent.CHANGE, abc);