有没有办法检测md-autocomplete material2+angular2上的选择面板是否正在显示？

import { Component, ViewChild } from '@angular/core';
import { MdAutocomplete } from '@angular/material';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.component.html',
  styleUrls: ['./your-component.component.css']
})
export class YourComponent {
  @ViewChild(MdAutocomplete) autocomplete: MdAutocomplete;

  // 其他代码...
}

onButtonClick() {
  if (this.autocomplete.panelOpen) {
    console.log('选择面板正在显示');
  } else {
    console.log('选择面板未显示');
  }
}