I'm pretty sure this is actually impossible in a distributed system with independent operation, and if it were possible, it would be terrible UI anyway.
Problem one is if you want to order events chronologically, you need to precisely decide what the time of the event means. Probably not the time the client hit send, because you can only measure that on the client and client clocks are at best approximately accurate. You could consider the time the server received it, and assume your server times are accurate, but that's still problematic because even in a well functioning system, if a user sends message A to server.wdc around the same time as a user sends message B to server.lax, users connected to server.wdc will get A then B, and users connected to server.lax will get B then A, and this leads to problem two:
Problem two is messages generally display in order of receipt. If you get a message that slots in earlier in the thread, you may need to scroll up to see it. In a busy theead, it's going to be hard to read all the messages because of the back and forth. If you send a message, it may need to be reordered too. If you go back to the thread later, new messages may be in different places. This is more disorienting IMHO than different message orders for different viewers.
Problem two gets even worse when you don't just have distance between servers, but also some network or other operational issues. If a server accepts a message, but is unable to forward it immediately, you probably want it to forward it whenever it can... if there's a significant delay, now the message is again going to be displayed in a place where it's difficult to see.
You can kind solve this by forcing messages to a group to go through a single queue which forces an ordering, but that makes accepting messages for a group a lot more difficult.