The second container has to be above the first one and:
private function init():void // call this on creationComplete event
{
container2.visible = false;
container1.addEventListener(MouseEvent.ROLL_OVER,overFunction);
container1.addEventListener(MouseEvent.ROLL_OUT,outFunction);
}
private function overFunction(e:MouseEvent):void
{
container2.visible = true;
}
private function outFunction(e:MouseEvent):void
{
container2.visible = false;
}
I would suggest that container1 should be 1-2 pixel larger than container2