Zhiyi Zhang (@zhiyi) commented about programs/winecfg/theme.c:
/* UXTHEME functions not in the headers */
+static const WCHAR *subkey = L"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize"; +static const WCHAR *name = L"AppsUseLightTheme";
Personally, I prefer you use string literals directly here. So it's get_reg_key(HKEY_CURRENT_USER, L"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize", L"AppsUseLightTheme", L"\0001");