this is my idea for multiple cursors and multiple focus, multiple keyboards, which could be could be an interesting User Interface. but I have learned that with only 1 mouse cursor or a shared screen, you have to have politeness toward the other person... :-)
could be interesting for collaborative stuff.
KVM Switches for multiple keyboards and collaboration for multiple cursors
could be switched over a UTP network cable, wifi, or via fiber, something with electrical isolation so as not to cause ground loops. people could sit alone at their desk and work, and when they need to collaborate, join in.
a shared window would be needed for this collaboration. sharing a whole desktop may be possible, but could be more intrusive, maybe antiproductive. this could be simply a shared application peer-to-peer client or client-server technology.