Comment 12 for bug 601816

Turns out that the Entry widget emits a preedit-changed signal, so latching onto that we can dynamically change the width of the preedit box.
The attached patch does just that. If you do not use an IME, it behaves exactly the same as normal kupfer. If you start to type using an IME, the preedit box pops out. Once you commit, the box hides again.

It works quite nicely for me with uim; we need someone to confirm with ibus.

If this works for everyone, then I recommend this patch as it is (baring any cleanups/restructures you suggest, of course).