hideMenu method
      
void
hideMenu()
      
     
    
隐藏菜单
Implementation
void hideMenu() {
  if (_disposed) return;
  if (_menuIsShowing) {
    _menuIsShowing = false;
    notifyListeners();
  }
}隐藏菜单
void hideMenu() {
  if (_disposed) return;
  if (_menuIsShowing) {
    _menuIsShowing = false;
    notifyListeners();
  }
}