Getting "Open" instead of "Download" for a Mime-type

[Dave Ahlswede <mightyquinn letterboxes org>]

I'm trying to figure out how Epiphany decides whether to offer the
Download or Open action in the file downloader dialog-- Specifically,
I'm trying to get it to open a .torrent file (gnomevfs-info from the
command line on the URL identifies it as application/x-bittorrent, and I
do have a mime handler set up for it)

Is it a property in the .desktop files, or is it somewhere else?