because these contain place-holder text and it doesn't make sense
to be able to edit them (unless some-day we support custom place-holder
prompts)
because they are now read-only add a pair of "show next level" and "hide
last level" features so on right clicking the last outline paragraph
you can make the next one visible, or make the last one invisible
Change-Id: Iea24d810f298156cfe2f32aa53d0515da45e08eb
7e600aca08