Window Header Colors?

Working on a theme for LMMS? Post progress and get feedback.
Hey all.

I'm working on a theme, and I want to replace that ugly purple gradient on the inner window tops with something more fitting. I can't seem to find either an image or a color in the default theme to alter it though. Any help is appreciated!
Could you post a screenshot of what you want to do? Also i'm not the best themer, but maybe i can help