In addition to the solution offered in that thread you can
also used Buddy API’s baOpenFile and specify a path to a
folder but don’t include a file name. If a valid folder path
without file name is provided baOpenFile will simply open the
folder. I know for sure this works on Windows, I believe it worked
on Mac a long time ago but I haven’t tested recently. The
convenient thing about using this method is that you can use the
same behavior to open both files and folders.