i looked at porting Ousterhout's Tk to Plan 9 several years ago,
but became discouraged.  i'd like to be more helpful but apart
from its size, i can't remember what ultimately discouraged me
from continuing.  there's a version for Windows so i suppose
X11 dependencies weren't the main problem, but perhaps
that was it.

the Inferno implementation was completely new,
and i think about 1/4 of the number of lines of Ousterhout's Tk at the time
(allow for Inferno's Tk being an extended subset of that Tk),
excluding Tcl.

i thought the Inferno implementation was tidier.