Hm, strange. I just did a fresh TW installation in virtualbox today, installed ibus, but Qt4/KDE4 applications do not crash when I entered text into a text field (tried kopete and qtconfig, I did right-click on the text field and check that ibus is selected as input method). Maybe the latest snapshot fixed it? Though I don't see anything relevant in the announcement mail... Can somebody else confirm that it's fixed, or is it still crashing for you?