_pickerWithSelectbox(pickerControl) {
    const selectlistWrap = document.createElement('div');
    const selectlist = document.createElement('select');
    const optionlist = document.createElement('ul');

    selectlistWrap.className = 'tui-image-editor-selectlist-wrap';
    optionlist.className = 'tui-image-editor-selectlist';

    selectlistWrap.appendChild(selectlist);
    selectlistWrap.appendChild(optionlist);

    this._makeSelectOptionList(selectlist);

    pickerControl.appendChild(selectlistWrap);
    pickerControl.style.height = PICKER_CONTROL_HEIGHT;

    this._drawSelectOptionList(selectlist, optionlist);
    this._pickerWithSelectboxForAddEvent(selectlist, optionlist);

    return selectlist;
  }
Make submenu control for picker & selectbox
@param {HTMLElement} pickerControl - pickerControl dom element
@returns {HTMLElement}
@private