@MrDSL mms.apk takes it from theme.holo.light
framework-res.apk\res\drawable-nodpi\background_holo_light.png
just an idea:
okay ill look into that tonight..
i may be wasting my time because i think cm9 will eventually add the black color option to Mms.apk like they did with cm7 but its hard for me to wait.
i do know I can flash a inverted Mms.apk and its all black without any framework changes.