[messaging] Minimal requirements for group chat

[Tom Ritter]

I do not think that threaded email conversations is the best mental
model - because threaded email conversations do not converge and they
definetly have an authoritative master (on a mailing list anyway).
When a threaded conversation on a list continues on two branches,
there is no mechanism for me to attach my reply to 'both' branches
(although I wonder what mail clients will do with two In-Reply-To
headers...)

But partially ordered chats do converge.  And my instinct from a UI
perspective is to represent the conversation 'side by side' to
represent 'they talked at the same time.'

Here Carol and Dave reply to Bob without seeing each other's messages,
but Tom has seen both

+--------------------------------------------------------------------+
| Bob, 3:45:11.234                                                   |
| Who wants to get Ice Cream?                                        |
+---------------------------------+----------------------------------+
| Carol, 3:45:12.412              | Dave, 3:45:12.567                |
| I do!                           | I don't but who wants to kill    |
|                                 | the president?                   |
+---------------------------------+----------------------------------+
| Tom, 3:45:12.987                                                   |
| Yes to the first, no to the second.                                |
+---------------------------------+----------------------------------+

It obviously gets more complicated.  Carol and Dave speak at the same
time. Earl has seen Dave's message but not Carol's.

+--------------------------------------------------------------------+
| Bob, 3:45:11.234                                                   |
| Who wants to get Ice Cream?                                        |
+--------------------+------------------------+----------------------+
|                    | Dave, 3:45:12.567      |
|                    | I don't but who wants  |
| Carol, 3:45:12.412 | to kill the president? |
| I do!              +------------------------+----------------------+
|                    |                        | Earl, 3:45:12.678    |
|                    |                        | That's intense. No   |
|                    |                        | one wants ice cream? |
+--------------------+                        +----------------------+
| Tom, 3:45:12.987                                                   |
| Yes to the first, no to the second. Carol and I do, Earl.          |
| (But I know you know that because of this bitchin UI.)             |
+--------------------------------------------------------------------+
| Trevor, 3:45:13.345                                                |
| Don't flatter yourself Tom.                                        |
+--------------------------------------------------------------------+

With this or similar UI, you also get to fix that super-annoying chat
frustration where you reieve a message in the millisec before you hit
enter.  Instead of having the client 'order' your message after the
just-recieved message, impose a delay (maybe with a color gradient
fade in the UI) when you're typing and a message arrives just before
you send your message. If you hit enter in that delay, your message
does not ACK the just-recieved message.

-tom