Use of emblems to combine generated thumbnail with file type icon

["David D. Lowe" <daviddlowe flimm gmail com>]

Are they any guidelines on the use of emblems to indicate file types?

Currently, gsf-office-thumbnailer generates previews for OpenOffice.org
and Office files. These previews are simply the front page's thumbnail.
This makes it difficult to distinguish between different kind of
documents, spreadsheets, presentations and drawings: they all look like
pieces of paper with minuscule text.

ooo-thumbnailer uses imagemagick to overlay the file type icon in a
corner. The trouble with this solution is that it cannot stay up-to-date
with the user's current icon theme.

A solution suggested by "migash.r" in a bug report [0] was to use
emblems instead. It seems quite elegant to me: keep with the current
icon theme without regenerating the thumbnails. However, it could
compete with any emblems that the user has set.

So what are the guidelines on emblems? Should we just follow Dropbox's
lead and define our own application-managed emblems?

David D Lowe

[0]
https://bugs.launchpad.net/ooo-thumbnailer/+bug/743962