Currently it is not possible to export more than one
set of thumbnails, it will only export thumbnails for 1
ABR file at a time. I have, literally, thousands of
brushes, so exporting the thumbnails for each file
singularly is tedious at best. Combined with having to
navigate to the destination folder every single time
makes this is very time consuming. You can select
multiple files in the "previewed sets" window, but it
won't export all that are selected. The multiple select
doesn't work properly either.
This is a great leap forward and a great tool, but
needs some additional polish and bug-fixes. I've been
hunting for a tool like this for quite some time, and
was very glad when I found it.
Please, keep up the development.