I just switched to qBittorrent about one week ago,
When I download torrent and I just check the files I want to download,
after the download is finished I find in the torrent folder other files is download,
Which is already unchecked from the beginning in Qbittorrent.
and I know about unwanted folder and I don't think It's related,
because I noticed It's creating unwanted folder when a checked files is downloaded or part of them,
and then when I uncheck these files, qBittorrent create the unwanted folder and transfer the files to that folder.
At the moment qBittorrent dumps the unselected files that contain cross-file-pieces in the same directory as the desired files.
This will change when libtorrent 1.1.x is officially supported by qbt.
Thank you thalieht.