Multiple thumbnail generators per MIME-type

["John Millikin" <jmillikin gmail com>]

Some MIME-types have multiple reasonable ways to generate a thumbnail
for any given file. Since the current thumbnail specification method
only supports one thumbnailer per MIME-type, not all files can be
thumbnailed. I propose that if a directory in
/desktop/gnome/thumbnailers has subdirectories, that each
subdirectory's command be registered with libgnomeui [1].

dobey on IRC suggested this might be covered by the XDG thumbnailing
specification [2]. However, this spec only covers the formats and
storage paths of thumbnails, with nothing about what executables are
used to create them. If anybody knows of a standard for the
registration of thumbnailer executables, FD.O or otherwise, I am eager
to read it.

[1] http://bugzilla.gnome.org/show_bug.cgi?id=497264
[2] http://web.archive.org/web/20070302090724/jens.triq.net/thumbnail-spec/index.html