Comment 7 for bug 601816

Here's a sample implementation of the first option (simple-ime for non-text mode, ime for text-mode).
The only caveat with that patch is that if you manually switch IMEs, it will reset it the next time you open text mode.

UIM doesn't have the same issue that ibus does with eating the characters, it seems, but I would imagine that this fixes it, as I can't even activate UIM when not in text mode.