public function setBorders(PHPRtfLite_Border_Format $borderFormat, $left = true, $top = true, $right = true, $bottom = true)
{
if ($this->_border === null) {
$this->_border = new PHPRtfLite_Border($this);
}
$this->_border->setBorders($borderFormat, $left, $top, $right, $bottom);
}