'alt text' function in flash?


I was wondering if there was a simple AS for an ‘alt text’ style function like what you use in html to display text as you mouseover buttons?
I have 2 scenes to my flash file. in scene 1 preloader and in scene 2 i have a large mc with multiple buttons, i would like people to be able to mouse over the buttons and get a alt text box with a short description of each button they mouseover.
Is this possible? It seems like it should be so simple like it is in html but i have no idea??