[users] Outliner

[Elchanan]

Greetings everyone,
 
In a post last week, I saw the word "outliner" or the like go by at one
point. I've looked a bit in the OO docs I have, and I can certainly find
information about building an outline. But what I am seeking is a true
"outliner", that it, something that allows me to expand and collapse
sections of my outline as I go. Does OO offer such capability/how?
 
If not, any suggestions?
 
Thanks,
Elchanan