Wrong keyboard in effect, anyone seeing that ?

This post is X-posted with npm.l10n, but follow-ups are to npm.i18n

I'd like to do an informal poll to see if other personn see the problem 
in bug 292602 :
https://bugzilla.mozilla.org/show_bug.cgi?id=292602

The reporter says the following :
> If I'm using one FF window for a "long" time, my keyboard layout (BE (Azerty))
> flas back to Qwerty.
> 
> This happens for no apperant reason and only happens in Firefox. My OS still
> indicates Azerty as the keyboard layout.

After reading that, I realized that I have seen several time a very 
similar effect. When Firefox/Seamonkey is selected, my keyboard behaves 
as EN (qwerty keyboard), even if the taskbar icons says the currently 
selected keyboard is FR (azerty keyboard).

Up until now, I thought this was OS problem/inadvertent ALt-Shift 
pressing related, but now I wonder if the Mozilla code isn't doing 
something wrong.

This is a hard one to link to specific steps for reproduction, but it 
would be very useful for investigation.