Remove the initial assignment for the key:
$ xfconf-query --channel xfce4-keyboard-shortcuts --property "/xfwm4/custom/<Super>d" --reset
Now add the shortcut:
$ xfconf-query --channel xfce4-keyboard-shortcuts --property "/xfwm4/custom/<Super>d" --create --type string --set "show_desktop_key" $ xfconf-query --channel xfce4-keyboard-shortcuts --list -v | grep -i super
Joel G Mathew, known in tech circles by the pseudonym Droidzone, is an opensource and programming enthusiast.
His favorite pastime is grappling with GNU compilers, discovering newer Linux secrets, writing scripts, hacking roms, and programs (nothing illegal), reading, blogging. and testing out the latest gadgets.
When away from the tech world, Dr Joel G. Mathew is a practising ENT Surgeon, busy with surgeries and clinical practise.