I use xfce4-notes in Xubuntu 14.04, und I have the possibility to show/hide the notes via the panel plugin in the notification tray. I will append images of this panel plugin because I can not find its exact name:


Every click on one of the icons toggles the visibility --- shows or hides the notes.
Now I would love to do that by keyboard shortcut. For that I need the command the panel buttons call. My Google-Fu failed me in that. Can you help me?