sputnikk, можно через реестр сделать.
Personalize
Код:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize]
"ColorPrevalence"=dword:00000001
"EnableTransparency"=dword:00000001
"AppsUseLightTheme"=dword:00000001
"SystemUsesLightTheme"=dword:00000000
"EnableBlurBehind"=dword:00000001