Dave is looking a good name for his new outliner.  These are some names I came up with just now:

• Op
• Opy
• OPed
• OPad
• Opal
• TreeTop
• OneTree
• nTree

Among them, I like the sound of Opy and nTree the best.  If I had to choose, I would go with nTree because it implies both in-tree and entry as well as any number of trees.  I also like the way the uppercase T sticks out like a tall tree rising above the forest.