The thunar-thumbnailers project provides additional thumbnailers for use by 
the Thunar file manager. Thumbnailers are little utilities that run in the 
background to generate previews for certain file types.

After installing this package, each user will need to execute the following 
command:
  /usr/libexec/thunar-vfs-update-thumbnailers-cache-1

Optional dependencies are dcraw (for raw image support) and ffmpegthumbnailer
(for video file support).  Both dcraw and ffmpegthumbnailer are available at 
SlackBuilds.org.  If you wish to enable support for either or both of these, 
you will need to edit the build script to do so - the required lines are 
commented out. If you choose to compile with dcraw (--enable-raw), you'll also 
need raw-thumbnailer, for which a script is present at slackbuilds.org.