How to install openbox on ubuntu 18.04

sudo apt install openbox

 sudo apt install openbox-gnome-session 

sudo apt install xcompmgr 

sudo apt install gnome-screensaver

 sudo apt install obmenu

add apps with commands like pavucontrol, kill tint2, tint2 etc you want

 sudo apt install pavucontrol 

 sudo apt install tint2

sudo apt install feh

feh --bg-scale /home/ronalds/Pictures/pexels-photo-1260820.jpeg

 sudo geany /etc/xdg/openbox/autostart.sh 

add:

eval `cat $HOME/.fehbg` &

tint2 &

 sudo nautilus /usr/share/applications

 sudo geany ~/.local/share/applications/lockscg.desktop 

[Desktop Entry] Type=Application Name=lock screen Exec=gnome-screensaver-command -l 

sudo geany ~/.local/share/applications/show-desktop.desktop 

[Desktop Entry] Type=Application Name=Show Desktop Icon=desktop Exec=xdotool key --clearmodifiers Super+d 

sudo geany ~/.config/tint2/tint2rc 

add:

 launcher_item_app = show-desktop.desktop

 launcher_item_app = nautilus.desktop 

launcher_item_app = gnome-terminal.desktop

 launcher_item_app = pavucontrol.desktop

 launcher_item_app = google-chrome.desktop

 launcher_item_app = lockscg.desktop

DON't forget to switch off going to hibernation on closing the lid, in the gnome-desktop-environment, if You don't really like Your laptop doing that in Openbox session.