pan_ox
tc->pan_ox = tty->oox;
if (tc->pan_ox > adjust)
tc->pan_ox -= adjust;
tc->pan_ox = 0;
tc->pan_ox += adjust;
if (tc->pan_ox > w->sx - tty->osx)
tc->pan_ox = w->sx - tty->osx;
c->pan_ox = 0;
else if (c->pan_ox + *sx > w->sx)
c->pan_ox = w->sx - *sx;
*ox = c->pan_ox;