public function dragDropXY($x, $y, $relative = null)
    {
        $arguments = array($x, $y);

        if (null !== $relative) {
            $arguments[] = (bool) $relative ? 'true' : 'false';
        }

        $this->con->executeStep(
            sprintf('_sahi._dragDropXY(%s, %s)', $this->getAccessor(), implode(', ', $arguments))
        );
    }