Hi,
Why is the difference between a regular folder and a dropbox folder?
If there's no difference I think you only need to filter which file extension do you want to read. The problem could be if you want to read all of the extensions except *.ini or this particular .ini file. There´s no a direct way to do it, I mean, with a dropdown list or a checkbox, but you could write an expresion to determine which files you want to process.
Hier is a great example.
Kind Regards.
Paul Hernández