Sorry for the late reply. The options in the picture you posted only works with xfwm4 window manager. If you type restartwm xfwm4 in the terminal, you will find that it will work.
To change the number of virtual desktops with " Joe's Window Manager", to need to edit a config file for it.
To do so, you can type the following in the terminal:
Code: Select all
geany /root/.jwm/jwmrc-personal
Hope that helps.