Thanks Six9siX to help us with our problem of the white background. It didn't work for me in my Windows 7 v.6.1 Edition Familial Premium

I have proceeded with both: a copy of your Aero.msstyles from your Basic&Aero.rar and a copy of the Windows 7 original. I've lost the transparency in both cases from executing the same steps in the same Classical-theme:
1) Save a copy of aero.msstyles in C:\Windows\Resources\Themes\Aero\
2) Open aero.msstyles in Restorator.
3) Extract the Variant\Normal in C:\Windows\Resources\Themes\Aero\NORMAL.res
4) Open NORMAL.res in XVI32.
5) Edit (FC FC FC) for my two different colors at adresses Hex: 0E188 and 2C1E0.
6) Save NORMAL.res in C:\Windows\Resources\Themes\Aero\
2) Reopen aero.msstyles in Restorator from C:\Windows\Resources\Themes\Aero\
7) Assign edited NORMAL.res from C:\Windows\Resources\Themes\Aero\
9) Save and log off.
10) Log in.
11) Change my Classical-theme for an Aero theme.
Results in both cases, e.g. your and the original copies of aero.msstyles in step 1:

No transparency and same color in the left and right panes of the Explorer
I hope I did a mistake instead of not working in Windows 7 v.6.1 Edition Familial Premium!!