The listbox pattern can be found at:
http://w3c.github.io/aria-practices/#Listbox

It is largely complete. Incomplete work includes:

1. 2 links in the notes to sections that have not yet been drafted.
2. There are several sentences that include "author should" language that should be revised to avoid normative sounding phrasing.

Requested reviews

• Review by @jnurthen
• Review by @accdc
• Review by @annabbott