Keyboard stopped working in KDE

Tue Mar 11 17:04:19 UTC 2014

F20 fully updated to KDE 4.12.3-1, x86_64, NVidia GT630 graphics with
the proprietary driver.

This morning everything was working. This afternoon, after updating
KDE, I no longer have a keyboard.

The KB does work in a non-desktop console, and also under Gnome (where
I'm typing this), but in no part of KDE.

KB hardware is a Microsoft Wireless Keyboard 800 connected via a USB
dongle. The mouse connects through the same dongle and is working
fine. That particular model is not listed as an option in the KDE
Settings widget, so I've been selecting "Microsoft Wireless Multimedia
Keyboard 1.0A".

This could be something silly related to evdev, but I've no idea what,
so ideas are welcome.

poc