自定义自动补全cellType增加下拉箭头并绑定事件

之前有个是自动补全下拉内容控件的需求，按照你们的帮助进行了实现代码如下：function AutocompleteCellType(availableTags) {
  this.availableTags = [];
  if (_.isArray(availableTags)) {
    this.availableTags = availableTags;
  }
}
AutocompleteCellType.prototype = new spreadNS.CellTypes.Base;
AutocompleteCellType.prototype.createEditorElement = function (context) {
  return document.createElement('input');
};
AutocompleteCellType.prototype.activateEditor = function (editorContext, cellStyle, cellRect, context) {
  var $editor = $(editorContext);
  spreadNS.CellTypes.Base.prototype.activateEditor.call(this, editorContext, cellStyle, cellRect, context);
  $editor.css('position', 'absolute');
  $editor.attr('gcUIElement', 'gcEditingInput');
  $editor.autocomplete({
    minLength: 0,
    source: this.availableTags
  }).focus(function() {
    $(this).autocomplete('search', $(this).val());
  });
  $editor.autocomplete('widget').attr('gcUIElement', 'gcEditingInput'); // keep focus when mouse down on dropdown
if(_.isEmpty($editor.val())){
    $editor.autocomplete('search', '');
  }
  return $editor;
};
AutocompleteCellType.prototype.deactivateEditor = function (editorContext, context) {
  if (editorContext) {
    var $editor = $(editorContext);
    $editor.autocomplete('destroy');
  }
  spreadNS.CellTypes.Base.prototype.deactivateEditor.call(this, editorContext, context);
};
AutocompleteCellType.prototype.setEditorValue = function (editorContext, value, context) {
  $(editorContext).val(value);
};
AutocompleteCellType.prototype.getEditorValue = function (editorContext, context) {
  return $(editorContext).val();
};
AutocompleteCellType.prototype.updateEditor = function (editorContext, cellStyle, cellRect, context) {
  if (editorContext) {
    var $editor = $(editorContext);
    $editor.css('width', cellRect.width);
    $editor.css('height', cellRect.height);
    $editor.css('outline', 'none');
    $editor.css('border', '0');
  }
};
AutocompleteCellType.prototype.isReservedKey = function (event, context) {
  var keyCode = _.get(event, 'keyCode');
  return context.isEditing && (_.isEqual(keyCode, 38) || _.isEqual(keyCode, 40));
};目前碰到一个问题是希望像下图中的B21单元格一样，增加一个下拉选图标并绑定相关事件，应该如何做：

无论是上面的自动补全还是层级的下拉框都是基于产品二次开发来实现的，想上面描述的具有补全提示且分层级的下拉框属于业务上的需求了。上面所说的两个demo就是大致实现思路，需自行再次改造实现，这边没有更好的实现建议。