Automatically resize a container when adding a component

Hi,

Why doesn't a parent container automatically resize when adding an element bigger than its width/heigth?
Isn't this considered the default behavior?

Here is my sample:

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx" >
<s:layout>
<s:VerticalLayout gap="10" />
</s:layout>

<fx:Script>
<![CDATA[
import spark.components.BorderContainer;
import spark.components.Button;

protected function clickHandler(event:MouseEvent):void {
var child:spark.components.Button = new spark.components.Button();
child.label = "Loooooooooooooog Label";

container.addElement(child);

]]>
</fx:Script>

<s:Button label="Add Button" click="clickHandler(event)" />
<s:VGroup id="container" width="50" height="50" />

</s:Application>