# Possible values are:
# * none: Don't do anything.
# * do_action: If the notification has exactly one action, or one is marked as default,
# invoke it. If there are multiple and no default, open the context menu.
# * close_current: Close current notification.
# * close_all: Close all notifications.
# Possible values are:
# * none: Don't do anything.
# * do_action: If the notification has exactly one action, or one is marked as default,
# invoke it. If there are multiple and no default, open the context menu.
# * close_current: Close current notification.
# * close_all: Close all notifications.