下拉菜单按钮组件

<div class="dropdown">
  <button class="btn btn-default"  data-toggle="dropdown" >
    Dropdown
    <span class="caret"></span>
  </button>
  <ul class="dropdown-menu">
    <li><a href="#">Action</a></li>
    <li><a href="#">Another action</a></li>
    <li><a href="#">Something else here</a></li>
    <li role="separator" class="divider"></li>
    <li><a href="#">Separated link</a></li>
  </ul>
</div>

**

设置菜单的分割线

**

<ul class="dropdown-menu" >
  ...
  <li class="divider"></li>
  ...
</ul>

**

禁用菜单选项

**

<ul class="dropdown-menu">
  <li><a href="#">Regular link</a></li>
  <li class="disabled"><a href="#">Disabled link</a></li>
  <li><a href="#">Another link</a></li>
</ul>