[flexcoders] Moving a viewStack through actionscript

[Wally Kolcz]

I have a test that I want to walk through the questions using a function. How 
can I set the inital value of the ViewStack (questionsVS) to 0 and then 
increment it by one each time someone clicks a button?

<mx:ViewStack id="questionsVS" width="98%" height="100%" paddingLeft="10">
        <questions:question1 />
        <questions:question2 />
        <questions:question3 />
        <questions:question4 />
    </mx:ViewStack>