예전에 ak47님께서 제게 보여주셨던 메뉴를 같이 벌레잡기 했던 소스코드입니다.
-새로고침해도 기존에 열려있는 게시판을 기억하는 똑똑한(?) 특징이 있습니다.
미리보기 http://gnusr.com/g4/gnusr/test/menu_test.php 에서  _test_menu_ak47
요청에 의해 올리지만 중복여부를 확인하지 못했습니다.(죄송합니다)

소스코드에서 $ca_id로 검색후 $gr_id 혹은 그룹아이디로 대체해주세요.
<?
if (!defined("_GNUBOARD_")) exit; // 개별 페이지 접근 불가
?>

<!-- 디자인 부분 -->
<style type="text/css">
.menutitle{
    cursor:pointer;
    margin-bottom: 2px;
    background-color:#CDCDCD;
    color:#000000;
    width:190px;
    padding:5px;
    text-align:left;
    font-weight:bold;
    border:0px solid #000000;
}

.submenu{    padding:5px; margin-left:35px; text-align:left; }
</style>

<script type="text/javascript">
var persistmenu="yes"
var persisttype="sitewide"

if (document.getElementById){
document.write('<style type="text/css">\n')
document.write('.submenu{display: none;}\n')
document.write('</style>\n')
}

// 메뉴전환
function SwitchMenu(obj){
    if(document.getElementById){
    var el = document.getElementById(obj);
    var ar = document.getElementById("masterdiv").getElementsByTagName("span");
        if(el.style.display != "block"){
            for (var i=0; i<ar.length; i++){
                if (ar[i].className=="submenu")
                ar[i].style.display = "none";
            }
            el.style.display = "block";
        }else{
            el.style.display = "none";
        }
    }
}

// 쿠키
function get_cookie(Name) {
    var search = Name + "="
    var returnvalue = "";
    if (document.cookie.length > 0) {
        offset = document.cookie.indexOf(search)
    if (offset != -1) {
        offset += search.length
        end = document.cookie.indexOf(";", offset);
    if (end == -1) end = document.cookie.length;
        returnvalue=unescape(document.cookie.substring(offset, end))
    }
}
return returnvalue;
}

function onloadfunction(){
    if (persistmenu=="yes"){
    var cookiename=(persisttype=="sitewide")? "switchmenu" : window.location.pathname
    var cookievalue=get_cookie(cookiename)
    if (cookievalue!="")
        document.getElementById(cookievalue).style.display="block"
    }
}

// 기존메뉴상태 보존
function savemenustate(){
    var inc=1, blockid=""
    while (document.getElementById("sub"+inc)){
    if (document.getElementById("sub"+inc).style.display=="block"){
        blockid="sub"+inc
    break
    }
    inc++
}
    var cookiename=(persisttype=="sitewide")? "switchmenu" : window.location.pathname
    var cookievalue=(persisttype=="sitewide")? blockid+";path=/" : blockid
    document.cookie=cookiename+"="+cookievalue
}

if (window.addEventListener)
    window.addEventListener("load", onloadfunction, false)
else if (window.attachEvent)
    window.attachEvent("onload", onloadfunction)
else if (document.getElementById)
    window.onload=onloadfunction

if (persistmenu=="yes" && document.getElementById)
window.onunload=savemenustate

</script>

<?
global $g4;
//해당그룹만
$sql = " select * from $g4[board_table]
where gr_id = '$ca_id' order by bo_subject ";
/*
//$sql = " select * from $g4[board_table] where bo_list_level = '1' order by bo_subject ";
$sql = " select * from $g4[board_table]
where gr_id <> 'work'
and gr_id <> 'montessori'
and gr_id <> 'etc'
and gr_id <> 'link'
order by bo_subject ";
*/
$result = sql_query($sql);

echo "<div id='masterdiv' align=center>";

$k="";
while ($row = mysql_fetch_array($result)) {
$k=$k+1;

if ($row[bo_use_category]==0) {
echo <<<HEREDOC
<div class="menutitle" onClick="location.href='$g4[bbs_path]/board.php?bo_table=$row[bo_table]'">&nbsp;&nbsp;{$row[bo_subject]}</div>
<span class="submenu" id="sub$k"></span>
HEREDOC;
continue;
}

else {
echo <<<HEREDOC
<div class="menutitle" onclick="SwitchMenu('sub$k')">&nbsp;&nbsp;{$row[bo_subject]}</div>
<span class="submenu" id="sub$k">
HEREDOC;

$arr = explode("|", $row[bo_category_list]); // 구분자가 | 로 되어 있음
echo <<<HEREDOC
<A HREF="$g4[bbs_path]/board.php?bo_table=$row[bo_table]&sca=">전체분류</A><br>
HEREDOC;
for ($i=0; $i<count($arr); $i++)

if (trim($arr[$i])) {
echo <<<HEREDOC
<A HREF="$g4[bbs_path]/board.php?bo_table=$row[bo_table]&sca=$arr[$i]">{$arr[$i]}</A><br>
HEREDOC;
}
echo "</span>";
}
}
echo "</div> ";

mysql_free_result($result);
?>