Sliding menu help!

Hi all,

Just have a quick question, which will hopefully recieve a quick simple answer.

I have completed the sliding menu tutorial found on this site, and I have built it up from the ground up with different graphics and everything works fine.

The question I have is how do you keep the button that is down, kept down.

For example, when the first panel is selected as you open the page, how do you keep button one in its downstate and so on.

An example of this is at www.thisisactualsize.com/main.html > work . work folders, and when you scroll on the portfolio using the buttons you can tell which of the buttons are down.

Cheers all!