Checking that ':;!?' are preceded by an unbreakable space in French would be nice. It would not be very hard to add that check.
But I wonder what's the official word is on unbreakable spaces. It's quite confusing because they seem to be used both in GUI elements (e.g. in comdlg32) and in things like usage and error messages that go to the terminal (e.g. cmd). Yet there is also about 205 locations that use a regular space or nothing instead. So is there circumstances where they must be avoided?
I added simple non-breaking space due to a variety of display problems for different apps. In fact, it's even more complicated since there are thin non-breaking space and normal-sized breaking spaces in French typography, and some chars are not present in certain unicode versions IIRC (+ a couple of various Windows bugs as well).
For more information, see for instance
http://malaria.perso.sfr.fr/fines/fines.pdf http://listes.traduc.org/pipermail/traduc/2010-August/006615.html (for the associated thread) http://traduc.org/gnomefr/Typographie
Frédéric