In order to build a multiplayer persistent world using Construct, the optimal construction seems to be that every area of the world is its own layout, which is then hosted 'peer-to-peer' whenever two players enter the same layout (rather than having a 'host' computer run the whole world on a single layout, which other players then connect to). So, for example, for a multiplayer Zelda-y world, every screen is its own layout, and if two players are on the same 'screen' of the world, they connect to each other; otherwise, they're not online.
This is all fine and dandy, but it creates a serious complication for player chat. My understanding is that the current way of accomplishing multiplayer chat requires players to be on the same layout together; so your world would have local chat at that point, but no global chat.
I'm sure there are alternate solutions, like piping in IRC or some sort of external chatroom externally. But within C2, would it be possible to simply layer a second 'layout' over the main game layout that just handles the chatroom? This way, all players would be on the same 'chat' layout and sync the chat through a multiplayer object on that layout.