you can't tell me
this system was designed with the idea of running it using text terminal
and no mouse. There is also no cursor addressing, no curses.
The well named Curses and the associated vi were an ugly outgrowth
of glass screens--an outgrowth many of us in the Unix lab never
adopted. That branch of evolution was unrelated to the Blit branch that
essentially preserved the old TTY interface, except that one could have
multiple terminals on screen and a mouse was available to give mechanical
help for manual cut/paste/edit activities. Plan 9 terminal-handling
smoothly continued that evolutionary branch.
Mouse support could have been used to take off in a radical direction,
but it wasn't. To my mind, the primary innovation in Plan 9 was not
terminal support, nor everything-is-a-file. Rather it was an advance in
what Vyssotsky called "distributable computing", where components can
collaborate in a uniform way, no matter where they are. The key was the 9P
protocol that unpacked the notion of file type--a unifying principle
that brought simplicity and generality to a diversity of particulars.