ctreeview 的展开收缩怎么控制？ [ 新手入门 ]

查看手册ctreeview 里有个control 属性不知怎么用。设置了'expanded'=>false，所以现在是缩的状态。不知道如何展开

<ul id="treeview" class="treeview">
<li id="treeList" class="closed expandable"><div class="hitarea closed-hitarea expandable-hitarea"></div><div class="treeviewParent">一级
</div><div class="treeLine treeSolid">
</div>
<ul style="display: none;">
<li><div class="treeviewList"><a href="#">二级</a>
</div><div class="treeLine">
</div></li>
<li><div class="treeviewList"><a href="#">二级</a>
</div><div class="treeLine">
</div></li>
<li class="last"><div class="treeviewList"><a href="#">一级</a>
</div><div class="treeLine">
</div></li>
</ul>
</li>
<li class="closed last"><div class="treeviewParent">二级
</div><div class="treeLine treeSolid">
</div></li>
</ul>