Scrolling list

Would anyone have any idea how I would go about making a scrolling list.

I have a class that brings in a list from an XML file and I drew mask over it. I added a scroll button that scrolls the list sprite up but I dont know how I can get it to stop scrolling up when the last item on the list is revealed. It would just keep going and going as long as my cursor is over the scroll button.

Any Suggestions or Know how?