Returned by useMentionAutocomplete to TextEditor.
mentionOpen: boolean
Set only once a search has found someone.
mentionSelectedIndex: number
syncMention: (value: string,pos: number,lookup: boolean) => void
Follows the @query under the caret, searches for it 150 ms after the
last keystroke, and closes the list once the caret leaves it. The caller
calls it on every change with lookup set, and on every caret move
without, since only typing may search.
closeMention: () => void
handleMentionKeyDown: (e: MentionKey) => boolean
Handles the arrows, Enter, Tab and Escape while the list is shown, and returns whether it took the key. The caller must then leave the key alone.
handleMentionSelect: (username: string) => void
Inserts @username through replace and closes the list.