DropdownMenu 下拉菜单

<re-dropdown-menu>
  <re-dropdown-item :options="productOptions" placement="right" :value="productValue" @change="onProductChange" />
  <re-dropdown-item :options="sorterOptions" placement="right" :defaultValue="sorterDefaultValue" />
  <re-dropdown-menu>
  <re-dropdown-item label="单列多选" :options="multipleSelectOptions" :value="multipleSelectValue" multiple @change="onMultipleSelectChange" />
  <re-dropdown-item label="双列多选" optionsColumns="2" :options="doubleColumnsOptions" :defaultValue="doubleColumnsDefaultValue" multiple />
  <re-dropdown-item label="三列多选" optionsColumns="3" :options="tripleColumnsOptions" :defaultValue="tripleColumnsDefaultValue" multiple />
  <re-dropdown-menu>
  <re-dropdown-item label="树形双列" optionsLayout="tree" :options="doubleColumnsTreeOptions" :value="doubleColumnsTreeValue" @change="onDoubleColumnsTreeChange" />
  <re-dropdown-item label="选项最多八字树形三列" optionsLayout="tree" :options="tripleColumnsTreeOptions" :defaultValue="tripleColumnsTreeDefaultValue" multiple />
  <re-dropdown-menu>
  <re-dropdown-item disabled label="禁用菜单" />
  <re-dropdown-item disabled label="禁用菜单" />