Encontrei uma solução possível aqui: link
No entanto, é muito usado por sua conta e risco.
This is an at your own Risk tutorial Create a Restore Point
Then, go here
Dark theme for Windows8 RTM by ~Nighthawk-F22 on deviantART
Then you will also need this,
Run the UXTheme Patcher
Will patch the following files and append .backup to the originals...
uxinit.dll uxtheme.dll themeui.dll
If you uninstall UXThemePatcher it is supposed to replace the original files back.
Then try to copy the files from the Visual Style in the first link (I used Theme Without Thin White Inline Frame) to C:\Windows\Resources\Themes
And overwrite the files.
If you have to take Ownership of the Themes folder, that is fine and then give Full Admin Rights to it and child objects. DO NOT TAKE OWNERSHIP OF THE SYSTEM32 FOLDER as a whole, or even your C: drive. ONLY the Themes folder. You have been warned.
You may have to reboot a couple of times, Also, when you change themes the first time, Windows may freak out, but just reboot and it should be OK. Otherwise, you may have to do a restore and try again.