Parent to child popup window

//creating new window popup
onclick="javascript:openwindow('registrar.php?statpos=course_curriculum&action=search_subject_curr&cc_id=21&ccch_id=2', 'change', '');"

//button from the class
$checkbox = "<input name=\'search_box\' onclick=\"searchSubjects(\'',csh.college_headers_subject_id,'\',\'',fsn.subjname_name,'\')\" type=\'checkbox\'  value=\"',csh.college_headers_subject_id,'\"  onclick=\'\'  />";



<script>
//searchInput is the id of the parent window
    function searchSubjects(subject_id,subject_name){

        opener.document.getElementById('searchInput').value = subject_id;
        window.close();

        }

</script>