code: function _listbox()
  {
    at.write(VT_SAVE_CURSOR); // save
  
    at.write(CSI + (LAST + 2) + ';' + (AGAIN - 2) + 'r');
    at.moveto(1, LAST + 2);
    //at.write(CSI + 'J'); // erase down
  
    KEYS.forEach(function(line, idx) {
      if (selected === idx) at.reverse();
      var ll = line.substr(0, process.stdout.columns - 2);
      at.write(CSI + '4G' + ll + ESC + 'D');
      if (selected === idx) at.reset();
    });
  
    _resetscroll();
    at.write(VT_RESTORE_CURSOR); // restore
    at.reset();
  }
docs: which index into KEYS is presently selected?