I don't know if it's a bug but I think so.
I installed twice Linux Mint Elyssa KDE Edition and I got the problem each time:
- Insert and start the live DVD
- Launch the installationn from the desktop
- Select French, time zone, keyboard FR, etc...
- Installation ok at this point.
Reboot and KDM have a wrong keyboard selection, it is in US
The solution is to use the command line in order to change "us" to "fr":
login (keyboard should be good in console mode)
sudo nano xorg.conf
In the InputDevice, Generic Keyboard, change XkbLayout "us" ou "fr"
This normaly fix the problem.
[using a Dell Latitude D620]