UI panel with React `useEffect` hook can't call `editDocument`

[pklaschka]

@cpryland

It wouldn’t be too hard, given an async editDocument() -called function. It can just await a promise that only fulfills when some input “settles down.”

Unfortunately, editDocument() locks the UI until resolved (cf. my comment at Debouncing input events in panels - #7 by pklaschka)…