I searched a little, but can not find much. This seems rather outdated and contains no examples. Is it possible? Should I just shut up and learn C already?
This project seems to be a Python implementation of the XFCE Panel plugin:
https://github.com/xfce-mirror/xfce4-rss-plugin
Also check out this white paper on the XFCE wiki:
Xfce Panel Plugins How