onTimer event causes a cascader to close its next level items

Steps to Reproduce

1. run the zul
2. open the cascader
3. click an item in the first level to open the 2nd level items
4. wait for onTimer even to be sent

Current Result

the cascader closes the 2nd-level items

Expected Result

the cascader keeps opening the 2nd-level items

Debug Information

In cascader.js

    onResponse: function onResponse() {
      if (this._redrawItemsFlag) {
        this._redrawItems();

        this._redrawItemsFlag = false;
      }
    },

Workaround

zk-5414.js