Aleksey Matveev blog

 
		<![CDATA[
			import mx.controls.Button;
			import mx.core.IFlexDisplayObject;
			override protected function createNavItem(label:String, icon:Class=null):IFlexDisplayObject{
				var navItem:Button = super.createNavItem(label,icon) as Button;
				navItem.addEventListener(MouseEvent.ROLL_OVER, mouseOverHandler, false, 0, true);
				navItem.addEventListener(MouseEvent.ROLL_OUT, mouseOutHandler, false, 0, true);
				return navItem;
			}
			private function mouseOverHandler(e:MouseEvent):void{
				var b:Button = e.target as Button;
 
				b.setStyle("textDecoration","underline");
			}
			private function mouseOutHandler(e:MouseEvent):void{
				var b:Button = e.target as Button;
 
				b.setStyle("textDecoration","none");
			}
		]]>