Default color change help

[digitalrex]

I've managed to skin 90% of the interface, but being brand new to this, I've run in to a snag.

I've gotten everything in my UI gray, and gotten rid of the brown, except for this one background that appears randomly. As you can see, the top is blue gray, but the bottom is brown. After an extensive search through the default DDS files, I don't see it anywhere in there. Is it XML coded somewhere or have I missed a graphic? And where is the EQII square button? I can't seem to find that one either.

I know, I'm blind - but any help would work, and thank you.