Gs tool
for PostScript feature of PDF Viewer plugin
http://pages.cs.wisc.edu/~ghost/
-Html2ps
- for HTML printing feature of Fancy plugin
- http://user.it.uu.se/~jan/html2ps.html
Indicate (>= 0.3.0)
for indicator feature of Notification plugin
https://launchpad.net/libindicator/