My idea was to use LhSetGlobalExclusiveACL(0,0).
Exclusive would mean to allow all threads not in the list. And since the list is empty, all threads are allowed.
But internally in LhSetACL there is a check for IsValidPointer which fails for 0, even though the size is also 0.
So currently I must specify a valid pointer to an array and size 0, even though the array is then not used.
The check should include the InThreadCount. e.g.:
if( InThreadCount!=0 && !IsValidPointer(InThreadIdList, InThreadCount * sizeof(ULONG)) )
And it would be very helpful to add a valid example for this in the documentation.