This is NOT originally my command, but I have long forgotten who to credit, so here is a command to display Ubuntu compose key's combos:
less "/usr/share/X11/locale/$(grep --max-count=1 "${LANG%.*}.UTF-8\$" /usr/share/X11/locale/locale.dir | cut --delimiter=/ --fields 1)/Compose"
Run this command to DISABLE ambient brightness changes in Ubuntu (this really annoyed me in recent updates):
gsettings set org.gnome.settings-daemon.plugins.power ambient-enabled false
You may need to log out and log in again to apply the setting