Unfortunetly this is exactly the reason I haven't been able to keep Classic up to date. I have asked SOE to implement global defined colors (ColorStyle) for a LONG time but it just hasn't happened. This means every color applied to every text element must be changed to support multiple color schemes.
Every once in a while (when I find the time) I'll do a batch find and replace to rip a new version of Classic but it doesn't happen as offten as I'd like.
RE the group window: the easiest method would be to add the following to each button object
Code:
FrameControl="True"
This makes the button use the window settings for the frame.
The other method is to use an OnHoverin and OnHoverout script to set each buttons visibility.