The default keyboard shortcut setting is in the file
/etc/xdg/openbox/lxde-pi-rc.xml
under the <keyboard> section.
There may also be an rc.xml setting file in the same folder for your reference
Your personal shortcuts, if they exists, is in
~/.config/openbox/lxde-pi-rc.xml
For examle, add the following in the <keyboard> section to move to adjacent desktop workspace
<keybind key="C-A-Left"> <action name="DesktopLeft"/> </keybind> <keybind key="C-A-Right"> <action name="DesktopRight"/> </keybind>
