How to change the window title bar background (SOLVED)

I have been playing around with the Prefs/Gui. I can modify a lot of things fine, such as the screen title bar. But, when I try and modify the Active Window Title Bar background to a solid colour then nothing happens.

I can modify things like the backdrop shadows and the border at the bottom of the window, but for some reason I just cannot change the colour of the Active/Inactive Window Title Bar background.

The default Active is like a blue to grey/white gradient from top to bottom. I just want a solid colour.

You have to remove the bitmap from Prefs/GUI->Styles. If that is set, it overrides the rest. Afterwards, you can change the window border colours as you wish.

Thanks for that. It worked.