And yes... this issue is looking more and more like there's a missing Qt plugin lib from my binary package that's the culprit here.
Roger, if you'd like to test if the following unofficial binary Sigil package solves your keyboard issue, I'd appreciate it (I believe you were using the 64-bit version?).
https://docs.google.com/file/d/0B5Cp...it?usp=sharing
Let me know if it resolves the problem and I'll get the 32-bit version uploaded and edit my Unofficial Linux Sigil thread.