Everything is in the Javascript Code. (Which you don't ever touch)

The only AS you need to do is.

First banner:
on (rollOver) {
getURL("javascript:ExpandableBanners.openAd();");
}

Second banner:
on (rollOut) {
getURL("javascript:ExpandableBanners.closeAd();");
}

It auto detects the dimensions of your expandable banner, so its very easy to change and edit.

It works incredibly well and allows you to focus solely on the design of the banners.