RegSaveKeyExW

Undocumented in source but is binding to Windows. You might be able to learn more by searching the web for its name.
nothrow extern (Windows)
static if(_WIN32_WINNT >= 0x501)
LONG
RegSaveKeyExW
(
HKEY
,
LPCWSTR
,
LPSECURITY_ATTRIBUTES
,
DWORD
)

Meta