Per keyboard layout settings
Currently keyboard layout can be set per window or global.
I'm using a laptop with a US layout and a USB keyboard with a spanish layout. I now have to switch layout when I move from my desk (with USB keyboard) to on-the-go (laptop keyboard).
If the layout was set per input device this would make things a lot easier.
Either both layouts and keyboards can work concurrently or the global layout is switched if the USB keyboard is plugged in.