@Doitsu
Thanks for your reply.
Yes, I use an "unofficial" Linux build which up to now seemed to work nicely.
This (not being able to type directly a ô) began with the 0.7 sery of Sigil, based on Qt5. I'll have to address your remark to DiapDealer who kindly presented me with some debs and avoided me the major hassle of having to compile.
