Element-ui中元素滚动时el-option超出元素区域的问题

<transition
 name="el-zoom-in-"
 @before-enter="handleMenuEnter"
 @after-leave="doDestroy">
 <el-select-menu
  ref="popper"
  :append-to-body="popperAppendToBody"
  v-show="visible && emptyText !== false">
  <el-scrollbar
   tag="ul"
   wrap-class="el-select-dropdown__wrap"
   view-class="el-select-dropdown__list"
   ref="scrollbar"
   :class="{ 'is-empty': !allowCreate && query && filteredOptionsCount === 0 }"
   v-show="options.length > 0 && !loading">
   <el-option
    :value="query"
    created
    v-if="showNewOption">
   </el-option>
   <slot></slot>
  </el-scrollbar>
  <p
   class="el-select-dropdown__empty"
   v-if="emptyText &&
    (!allowCreate || loading || (allowCreate && options.length === 0 ))">
   {{ emptyText }}
  </p>
 </el-select-menu>
</transition>

handleClose() {
  this.visible = false;
},

<template>
 <div
  class="el-select"
  :class="[selectSize ? 'el-select--' + selectSize : '']"
  @click.s="toggleMenu"
  v-clickoutside="handleClose">
  后面的省略...

// src/mixins/fackClickOutSide.js
let lock = true;
let el = null;
const MousedownEvent = new Event('mousedown', {bubbles:true});
const MouseupEvent = new Event('mouseup', {bubbles:true});
const fakeClickOutSide = () => {
 document.dispatchEvent(MousedownEvent);
 document.dispatchEvent(MouseupEvent);
 lock = true; // console.log('dispatchEvent');
};
const mousedownHandle = e => {
 let classList = e.target.classList;
 if(classList.contains('el-select__caret') || classList.contains('el-input__inner')) {
  lock = false;
  return;
 }
 if(lock) return;
 fakeClickOutSide();
};
const mousewheelHandle = e => {
 if(lock || e.target.classList.contains('el-select-dropdown__item') || e.target.parentNode.classList.contains('el-select-dropdown__item')) return;
 fakeClickOutSide();
};
const eventListener = (type) => {
 el[type + 'EventListener']('mousedown', mousedownHandle);
 window[type + 'EventListener']('mousewheel', mousewheelHandle);
 window[type + 'EventListener']('DOMMouseScroll', mousewheelHandle); // fireFox 3.5+ 
}
export default {
 mounted() {
  el = this.$root.$el;
  el.addFakeClickOutSideEventCount = el.addFakeClickOutSideEventCount || 0;
  (! el.addFakeClickOutSideEventCount) && this.$nextTick(() => {
   eventListener('add');
  });
  el.addFakeClickOutSideEventCount += 1;
 },
 destroyed() {
  eventListener('remove');
  el.addFakeClickOutSideEventCount -= 1;
 },
}

// src/App.vue
import fakeClickOutSide from '@/mixins/fakeClickOutSide.js'
export default {
  name: 'App',
  mixins: [fakeClickOutSide],
}