Mouse Follow Boundary Help [AS2.0]

Hi All,
I’m new to this forum and to Flash. I’ve been given a site editing project which I’ve managed to struggle through until now :-/

I’ve uploaded a picture to help me describe what I need to accomplish. Please keep in mind that I know little about Flash and less about Action Script so if I appear to be :stare: don’t mind me. So here goes…

[URL=http://g.imageshack.us/thpix.php]

So I have a menu button along the left most side of my stage and I would like it to follow the mouse vertically only and only between the red line boundary.

Additionally when the button is clicked I would like the menu to stop and the secondary menu to to fade into sight, although I believe I can figure that part out with enough patience. The menu follow boundary is my main issue.

Any and all help would be greatly appreciated!

Cheers!