operating with non-existent files

[Saulius Krasuckas]

When I operate with "c:\nonexist_subdir" and "c:\\nonexist_subdir"
filenames in Wine and in NT5, most of API functions set the same
LastError.  That functions are:

OpenFile()
CreateFileA()
SetCurrentDirectoryA()
FindFirstFileA()
GetFileAttributesA()

But if I call this:
  IShellFolder_ParseDisplayName(IDesktopFolder, NULL, NULL, cNonExistDirW,
NULL, &newPIDL, 0)

then I get two different codes:
* for the first one HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND),
* for the second one E_FAIL.

This is true for winME and win2k (and not for Wine).

Do we need to distinguish between these two filenames in Wine?
If so, on top of what functions should it be implemented?

Do someone know, how native IShellFolder_ParseDisplayName works in the 
case of IDesktopFolder?  I think the double-slash in the filename has 
something to do with object names, but I have no ground here.