Change Raspbian windows manager to Openbox

To change default windows manager open:

sudo nano /usr/bin/x-session-manager

Replace the last line:

exec /usr/bin/lxsession -s LXDE-pi -e LXDE

with

exec /usr/bin/openbox-session

Alternative you can use one command:

sudo sed -ri "s/exec \/usr\/bin\/lxsession -s LXDE-pi -e LXDE/exec \/usr\/bin\/openbox-session/" /usr/bin/x-session-manager

or change back to original:

sudo sed -ri "s/exec \/usr\/bin\/openbox-session/exec \/usr\/bin\/lxsession -s LXDE-pi -e LXDE/" /usr/bin/x-session-manager