Spark Application Layout Questions

Question

Just started playing out with Flex 4 Beta...
Does anyone know the reasoning why spark application's layout property has to be set to a new instance of a layoutContainer?  For instance, in my MXML I have to say layout="{new spark.layouts.VerticalLayout()}".  With halo I could do layout="Vertical".
Are there new enhancements to the spark components with regards to layouts that prompted this change?  What cool new things can I do with them?
Thanks,
Bryan

Answer 1

And another cool thing you can do with the new layout system is change values using the new states syntax:
<?xml version="1.0"?><s:Application 
xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark">
<s:layout>
    <s:VerticalLayout gap="24" gap.state2="4"            paddingLeft="
20" paddingTop="20" /> 
</s:layout>
<s:states>
    <s:State name="state1" /> 
    <s:State name="state2" /> 
</s:states>
<s:HGroup>
    <s:Button label="goto state1" click="currentState='state1';" /> 
    <s:Button label="goto state2" click="currentState='state2';" /> 
</s:HGroup>
<s:Button label="Button 1" /> 
<s:Button label="Button 2" /> 
<s:Button label="Button 3" /> 
<s:Button label="Button 4" />
</s:Application>
Using the code above, the default/state1 state will use a vertial gap of 24 pixels, while state2 will use a vertical gap of only 4 pixels.
Peter