Log Message:
Update xfce4-genmon-plugin to 4.0.0:

4.0.0 (2017/02/25)
==================
- Fix PangoFontDescription not being able to display initial default string

3.99 (2016/11/02)
================
 - Port to Gtk3
 - Fix font styling to work with Gtk 3.22
 - Add support for "genmon" in 'xfce4-panel --plugin-event' (Bug #10734)
 - Fix default tooltip does not work (bug #11284)
 - Add <txtclick> functionality (Bug #3437)