In Battery info dialogue, it would be nice if xfpm displayed the percentage that last full is relative to design. For example, Design: 59400 mWh Last full: 56507 mWh (95.1%)
Pushed a fix for this to git master: http://git.xfce.org/xfce/xfce4-power-manager/commit/?id=47d4ba88c43f97427746839363bced83e191afc1