destoon调用模块 如果有分类 下拉分类

<div class="head_banner" id="navi">
            <div class="bn_bt index">
              <a href="/" class="bn_a">网站首页</a>
            </div>
            {loop $MODULE $m}{if $m[ismenu]}
            <?php
                $a=$a+1;
            ?>
            <div class="bn_bt" >
              <a href="{$m[linkurl]}" class="bn_a">{$m[name]}</a>
              {php $child = get_maincat(0, $m[moduleid], 1);}
              {if $child!=null}
              <div style="display:none;" class="slider" id="slider{$a-1}">
                <div class="lilt_pt">
                  <img width="16" height="12" src="{DT_SKIN}picture/prompt_top.png">
                  </div>
                  <ul class="clearfix">
                    {loop $child $i $t}
                    <li>
                      <a href="{$m[linkurl]}{$t[linkurl]}">{$t[catname]}</a>
                    </li>
                    {/loop}
                  </ul>
                </div>
                {/if}
              </div>
              {/if}{/loop}
            </div>