import fl.containers.ScrollPane;
import fl.events.ScrollEvent;
import fl.controls.ScrollBarDirection;

var myScrollPane:ScrollPane = new ScrollPane();
myScrollPane.scrollDrag = true;
myScrollPane.source = "http://www.helpexamples.com/flash/images/image1.jpg";
myScrollPane.addEventListener(ScrollEvent.SCROLL, scrollHandler);
addChild(myScrollPane);

function scrollHandler(event:ScrollEvent):void {
    switch (event.direction) {
        case ScrollBarDirection.HORIZONTAL:
            trace("horizontal scroll", event.position, "of", event.currentTarget.maxHorizontalScrollPosition);
            break;
        case ScrollBarDirection.VERTICAL:
            trace("vertical scroll", event.position, "of", event.currentTarget.maxVerticalScrollPosition);
            break;
    }
}