Avoid collisions

[david-brt]

problem

• if a user has received a message but has not sent an answer, another user will see the same message
• if both users respond, there are now two unread messages in the database, only the more recent of which will be displayed

possible solution

• show each message only once, regardless of whether it has been answered or not
• set a cookie that indicates the shown message so if no response is sent, the receiver will be shown the same message until the old one is answered; mark the displayed message as unanswered in the database
• If there is a new user and no unread message, show him a random unanswered one
• this is not a perfect solution however as the cookie might be deleted, so user accounts mandatory logins would help

[david-brt]

better solution: add button that shows you a new message if there are multiple unread ones