Having a strong service-oriented background, my interest in reusable software is rather high. Ideally, most parts in service and component development would be reusable with well-defined interfaces and loose coupling.
In KDE land, we're now forging plans for 4.3 features and are faced with the undesirable dilemma of growing social software on the one hand (good!), but horrible widget inconsistencies on the other hand (not good!). The area of chat widgets is such an inpatient in need of consistency-increasing medication. Chat widgets are used in (drumroll...) chat applications, but also in online games, collaborative text editors and office applications, and just about anything else which has humans connected to it. In short, we do have a need for a chat widget set shared at the kdelibs level to increase consistency and cut down the number of redundant codelines in the already infinitely growing codebase. SoC candidates, anyone?
However, the search for a suitable candidate with a reasonable set of features is not easy. Let's follow good habits here by looking at the candidates:
KGGZ (part of the KDE3-based ggz-kde-client package) uses its own chat widget based on Qt classes. It offers nickname autocompletion, history, colouring and everything including the kitchensync, but is clearly protocol-specific and would need porting anyway.
Vencedor (heading towards kdegames) uses the KChat class from libkdegames. It is rather old, not maintained, doesn't look fancy and is domain-specific for games, especially two-player games.
KBattleship, despite being part of kdegames, uses its own chat widget! It's rather small and not nice or featureful, but at least it's generic.
Kopete uses its own chat widget which is rather flexible and full of cross-protocol features, including spell checkers and whatnot. According to its developers it should be possible to make it reusable by relying on the libkopete interface, but so far this still resides in kdenetwork and won't move due to ABI compatibility concerns. There are some interesting ideas currently being discussed, though, so it could still be possible.
Quassel uses its own chat widget. This IRC client receives a lot of developer and user attention at the moment, but according to its developers is not easily reusable.
Let's also follow really good habits by looking at the friendly competition:
Gobby uses its own chat widget based on GTKmm which is clearly Gobby-specific. It provides history, but no nickname autocompletion or emoticons.
GGZ-Gtk uses XText, the quite reusable XChat widget, which has almost all of the features one needs. However, the last time we merged the latest XText codebase, a lot of compiler warnings and some errors were introduced and have been there ever since. Not sure if XText is still maintained at all.
GGZ-Java uses its own chat widget based on AWT/Swing which is clearly GGZ-specific. The features are certainly sufficient for online gaming, and it's stylable with CSS. And, oops, I just spotted a bug where it assumes the name of the chatbot to always equal "MegaGrub".
To summarise, most people like to reinvent the wheel, and despite having been one of them in the past I'd like to see some consolidated generic chat widget becoming available to any KDE application.