Thumbs not show if change root directory

Hello,
thanks for elfinder module it's very good file manager. I install it in a drupal site and it works fine. If i change the "Root directory" from "Use system defaults (sites/default/files)" to "Specify custom path" for set a directory user, i can't see the thumbs (the temporany directory is .tmp and after change the root directory it created in new path and the are all image thumbs). So if my new root directory is:

sites/default/files/uploads

and tmp dir is .tmp
i have sites/default/files/uploads/.tmp where there are files for thumbnails but i don't watch this in the file manager. I don't want install the dev version so if it's possibile to change some line code for me it's better.

Thanks