Question: Is GUI multithreading considered?

I'm investigating the code of cosmoe-wayland compared to Haiku.

I know cosmoe-wayland does not have app_server because it says server-less, but I noticed it calls the wayland client code directly instead of sending messages to app_server.

In BeAPI, it is common for the GUI to have multiple threads, but I believe drawing requests from multiple threads were serialized by sending messages to the app_server.

Is cosmoe-wayland considering this case? Personally, I feel that it is necessary to solve it with a worker thread using ring buffer, etc.