Per device configuration

[rraafays]

There are certain modifications I make to my laptop's internal keyboard which I would like to not apply to my HHKB which I understand can be achieved by defining only my internal keyboard under devices: however I would also love certain things to be shared between the two such as using space as a function key to turn hjkl into arrow keys and sdfg into mousekeys.

Please let me know if this is something you're looking to implement or if I have just completely misunderstood or misread something.