Yes, it works your way too. On Kunbuntu the fiddling is a bit different, use:
Configuration systeme (System settings) > Region et langue (Region and language) > Model: any generic key PC will do (I use 105 key) | Layout variant: Défaut (Default)
It's the Alternative variant that causes the bug (-variant oss and subvariants like oss_latin9). With -variant unspecified, it's OK.
Still, I wonder whether the bug is Ubuntu's, Wx's, or C::B's ...