[Thunar-dev] Thumbnails - Mime-types

[david]

I'm trying to create a thumbnailing script.
The target  file is either an xml-file or a compressed xml-file and the
mime-types is the quite generic "text/plain" and "application/x-gzip"
Is there some way I can be more specific, like use the file extension
which is .sif or .sifz?

My script does not work at all right now and I'm pretty sure it has to
do with this issue here.

Thank you,
-David