_changeMenu(menuName, toggle, discardSelection) {
    if (this.submenu) {
      this._buttonElements[this.submenu].classList.remove('active');
      this._mainElement.classList.remove(`tui-image-editor-menu-${this.submenu}`);
      if (discardSelection) {
        this._actions.main.discardSelection();
      }
      this._actions.main.changeSelectableAll(true);
      this[this.submenu].changeStandbyMode();
    }

    if (this.submenu === menuName && toggle) {
      this.submenu = null;
    } else {
      this._buttonElements[menuName].classList.add('active');
      this._mainElement.classList.add(`tui-image-editor-menu-${menuName}`);
      this.submenu = menuName;
      this[this.submenu].changeStartMode();
    }

    this.resizeEditor();
  }
change menu
@param {string} menuName - menu name
@param {boolean} toggle - whether toggle or not
@param {boolean} discardSelection - discard selection
@private