In Windows 7 one could go into the Desktop Personalization panel, choose Window Color, then Advanced Appearance Settings... to make changes to things like the Caption Button sizes, Border Padding, etc. Just to be clear, this is the Windows 7 panel I'm describing:
With the Windows 8 Aero desktop we're missing this ability. I even turned on the GodMode configuration panel and I don't see a Window Color and Appearance panel.
The ability to tune up the traditional desktop really needs to be retained with Windows 8. Sorry if it's harder to support, but some of us really like to maximize the space for doing work and minimize the chrome in the multi-window environment!
Something you can try;
Remember that this is a Pre-Beta product and some features may not be available, but, if you want, I think you can export the registry key that has all colors changes that you need from:
HKEY_CURRENT_USER\Control Panel\Colors
So, you can import it into Windows Developer Preview and restart your system.