There are several Catalan locale codes that can be presently be used in X11 systems; specially after they were accepted in belocs-locale-data (http://lists.debian.org/debian-devel-changes/2005/07/msg01429.html)
In the following patches, I add ca_AD, ca_FR and ca_IT Catalan locale codes.
For instance, without this, using ca_AD (actually a quite used locale, as you can check in places like here -> https://launchpad.net/~ubuntu.cat/+members ) some applications (eg. Emacs or Skype) cannot display Catalan diacritic marks as you type them.
Created attachment 9962 [details] [review]
Catalan compose.dir.pre patch
Created attachment 9963 [details] [review]
Catalan locale.alias.pre patch
Created attachment 9964 [details] [review]
Catalan locale.dir.pre patch
fixed in commit eff33ae525337ce2026be135a26464c7b1237113.