This prevents a race condition where the console may still be rendering,
but the process may be able to get data on the screen faster, which results
in visual corruption as the two race.
Unfortunately this area is not standardized by POSIX. Linux uses an ioctl
which is not that bad, but I'd like to have a designated function. I'm not
sure if this facility is powerful enough and whether it should be improved.
Also note that I use a struct winsize as on Linux, but I use size_ts instead
for the heck of it. Perhaps I should use another name for the struct.
