侧面有一个箭头，打开子菜单。我无法点击chrome中的下拉列表，而是在ie。
中工作我尝试了悬停，点击和操作也是如此。但它不起作用。
代码如下：
<div id="navigatortab" class=" x-plain undefined sd_nav_tabpanel x-border-panel" style="left: 0px; top: 0px; width: 1600px;">
<div id="ext-gen32" class="support-servicedesk-navigator">
<table id="ext-comp-1014" class="x-btn support-servicedesk-sb support-servicedesk-sbactive caseMru x-btn-noicon" cellspacing="0" style="width: 180px; height: 26px; background-image: none; background-color: transparent;">
<tbody class="x-btn-small x-btn-icon-small-left">
<tr>
<tr>
<td class="x-btn-ml">
<td class="x-btn-mc">
<em id="ext-gen41" class="x-btn-split" unselectable="on">
<button id="ext-gen33" class=" x-btn-text" type="button">
<div class="mruIcon"></div>
<span>Cases</span>
</button>
</em>
</td>
<td class="x-btn-mr">
</tr>
<tr>
</tbody>
</table>
</div>