theme function "collapsed" argument correction

Please correct me if I am wrong. Recently a was checking ctools_ajax_sample module and found such output by default:
div collapsed
So my first thought - that div originally should be hidden.
Than i checked module code:
$output .= theme('ctools_collapsible', array('handle' => $handle, 'content' => $content, 'collapsed' => FALSE));
So div should not be collapsed but it is.
Thanks.