It appears to me that the `expanded/collapsed` part of the names got switched around, since I'd expect the following convention:
- `v` == expanded
- `>` == collapsed
- This commit adds a '>' before every outline item that has subitems.
- Click on the '>' to collapse all subitems under that item (which turns
the '>' in a 'v').
- Shift + click expands/collapses all descendant items under that tree.
- Double-clicking on the "Show Document Outline" button in the toolbar
expands/collapses all outline items.