Bug#661754: x11-xkb-utils: setxkbmap and xkbcomp settings do not apply to new keyboards
> Oh, I'm not saying it's possible today, I'm saying it's where it should
> be happening (it knows when a device gets plugged in, it has some
> knowledge of input device configuration, so making that per-device
> should be possible). If gsd isn't suitable, it shouldn't be too hard to
> write a program listening for DevicePresence events and doing whatever
> config is necessary for new devices.
That seems way too complicated: the X server already has the notion of
an InputClass section and setxkbmap is already a way to dynamically
specify an InputDevice section, so all that's needed is a way to
pass dynamically to the X server an InputClass section.