Fubar underneath UI elements

[Proeliata]

I just downloaded Fubar today, and I love it, but I have one problem with it--I'd really like to be able to have it go underneath my UI as opposed to over it. That is, if I move my unit frames on top of a Fubar bar, I'd like the unit frame to be the thing that's on top and not the Fubar bar.

Is there any way to do this?

Thank you!