Notification sounds are based on Create Commons licensed sound effects
from freesound.org

chat.wav: https://www.freesound.org/people/TheGertz/sounds/235911/
login/logout.wav: https://www.freesound.org/people/shall555/sounds/72197/
marker.wav: http://freesound.org/people/joedeshon/sounds/145805/
lock/unlock.wav: https://www.freesound.org/people/eizzof/sounds/190035/

