public function moveCursorRel($x, $y)
    {
        $yChar = ($y < 0) ? "A" : "B"; // up / down
        $xChar = ($x < 0) ? "D" : "C"; // left / right
        fwrite(STDOUT, "\e[" . abs($x) . $xChar);
        fwrite(STDOUT, "\e[" . abs($y) . $yChar);
    }