I have two xfce4-panel windows running and am using
wmctrl -x -a xfce4-panel -b add,below to make them both hide under windows, but only the panel 0 actually goes below windows. The second panel, panel 1, only hides below windows if I manually tell it to using
wmctrl -a :SELECT: -b add,below.
So, how do I make both panels hide below windows? Using xfce4-panel built-in hide features is out of question.