How to disable/remove Tree Component's Background?

I am using Flash MX 2004 Professional.

I am building an application which uses the Tree Component over a movie clip.

Is it possible to remove/disable/hide the white background of the tree component, so that it seems as if the tree menu is floating above the movie clip ?.

I am using default Halo Theme.

Please help me.

Thanks in advance.

Kannan.