Typing a period closes mention suggestion list, even if there are matching users

[robertknight]

When typing a period while the mention suggestion list is visible, the list will close even if there are matching members.

In this case:

Typing "." will close the suggestion list rather than filter it to the user whose name begins with "al."

IIRC the reason for this behavior is because we wanted to hide the suggestion list if you end a sentence with a mention ("This looks interesting @robertknight."), as opposed to showing a "no users matched" message. Hypothesis usernames can contain periods, which creates an ambiguity. A possible solution would be to hide the suggestion list only if there are no matches.

Slack thread