Really simple effect that I still ca't figure out!

Hi, I’m having trouble with something and I’d really appreciate some input.

There’s a professional website that has an effect I like but I don’t know how they did it.

When you scroll over the buttons, the words slide upwards and a different set slides into it’s place. The objects/movement are only visible within a rectangle that is as high as the letters. It’s fairly simple looking but trickier than I expected.

How is this done? I thought (since I’m pretty basic at Flash) that maybe there were white boxes above and below the words, making only the words visible when they were in the center area. But this can’t be how it’s done becuase I think that would cover up the words on the other lines.

I typed this in a longer entry a minute ago but it timed out and I lost it when I had to re-login. Hopefully by keeping it shorter, I’ll confuse less people than my lengthy description before! :beam: Thanks, I appreciate any input.