Exactly, the "systray" thing that is needed to switch the keyboard betweeen qubes. Dom0 would not even be accessible from USB-keyboards, for USB-related security reasons.
>>orbliv+71
I use the latest version of qubes and sys-usb and I don't ever reassign my usb keyboard(I do for other usb devices.) It sounds like the person from the top comment just configured their system in an annoying way.