dcgui (or Devchat GUI, I never bothered giving it a proper name) is a desktop client for Egosoft's Devchat, which is, despite its name, a general purpose chat for their games (one of the unique features of the chat are its chat levels, which allow completely different threads in a single chat room, thus multiplexing 5 separate development team chats and a general chat, as well as private messages, into one room).
It has multiple advantages over Egosoft's old official web client:
Private messages into separated tabs for improved visibility
More smileys and similar goodies
More resilient against server bugs
The web client only works fully reliable in Microsoft Internet Explorer. Six. Yeah, it's that old. Thus, stuff like persistent settings, audio notifications, persistent preset texts, full keyboard controls etc. are, while theoretically available for the browser chat as well, only fully supported in this client.
Joinmessage hider, destealther, and similar tools to introduce some checks and balances against abuse of certain chat server problems (or just plain spam)
Customisable chat colors (want greenies to have pink nick names? Nothing prevents you from doing so, apart from good taste. Maybe)
Better notification support. Not only beeps on certain keywords, but also sends visual notifications if supported by the OS (and allows you to trigger custom commands).
Customizable refresh rate – allows to either improve the performance of the chat, or reduce network traffic
The probably most important feature is that it can pass through messages to the Ingame Client, made by mark_a_condren and bundled with the client:
We can neither confirm nor deny any rumours that moderators are able to blow up your ship remotely. Best not try to find out.
This allows you to chat while in game without alt-tabbing out of it.
The client is considered to be in stable phase. There are no real stopper bugs, and all necessary features are implemented. Bug fixes will be provided when necessary, but further development is currently on hold – there's just not enough activity at Egosoft to warrant it.