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function ExtendedUserName: String;
  var
    GetUserNameEx: function(NameFormat: Cardinal; lpNameBuffer: PChar; var dwSize: Cardinal): Boolean; stdcall;
    hDLL: Integer;
    dwSize: Cardinal;
begin
  Result := '';
  try
    hDLL := LoadLibrary('secur32.dll');
    if (hDLL = 0) then begin
      Result := CurrentUserNameShort;
      Exit;
    end
    else begin
      GetUserNameEx := GetProcAddress(hDll,'GetUserNameExA');
      if (@GetUserNameEx = NIL) then begin
        CloseHandle(hDLL);
        Result := CurrentUserNameShort;
      end
      else begin
        dwSize := MAX_PATH;
        SetLength(Result,dwSize);
        If (GetUserNameEx(NameSamCompatible,PChar(Result),dwSize) and (dwSIze > 0) ) then
          Result := PChar(Result)
        else
          Result := CurrentUserNameShort;
      end;
      FreeLibrary(hDLL);
    end;
  except
  end;
end;