Last modified: 2011-03-13 18:06:44 UTC
Please add a new option to filter [[Special:Allmessages]] by extension (MakeBot, Makesysop, Check User, etc). The page size is currently very large (332 KB in enwiki) and difficult to preview.
Extensions tend to register messages prefixed with their own name (and this practice should be encouraged), so it's quite straightforward to pick out their exclusive messages on Special:Allmessages using the existing filtering option.
I'm not sure it's worth adding additional complexities to the message cache (i.e. in order to allow the indication of a message's source) to facilitate stronger filtering than this. If the existing prefix filter isn't adequate, then that should be improved.