I tried to eleminite the white color which was possible in Windows XP. With windows 8 unfortunately it seems that you have to use Window Blinds to get the best effort, but still can't eliminate everything.
File explorer, Mail client, etc. everything is in grey now. However, some save dialogues and the whole Stardock software itself still remains white.
Which leads me to the following questions:
Did I overlook some white spots I still could modify?
Does Stardock software make use of the customizations I did with it or does it always have the same background colors?
Here is an example what it looks now: I used the NebariGrey style and adjusted colors manually (turning still about 5 remaining white things into grey too):