Ubutntu jaunty by default uses IBus 0.1.
0.1 out of box doesn't allow you to write C code which handles the lookup-table and the auxiliary-text. 0.1 expects you to do this in python. These missing features in C are no showstoppers since most of the UIs are written in python anyway.
With the latest 1.2, these features are added on the C side too, so I wanted to upgrade from 0.1 to 1.2. Some APIs changed here and there, but nothing so major as far as I feel.
During the upgrade, I had to spend sometime to understand why [ja:anthy] didn't appear in the "preload_engines" gconf entry. I assume this is caused by the old gconf setting from the 0.1 time.
I think all the enablers for the C implementation is ready now, I just need more time.