Steps to Reproduce

Click radio "index0", and check the selectedIndex.

<zk>
    <div>
      <radio label='index0' radiogroup="rg1"/>
      <separator/>
      <radiogroup id='rg1'>
          <radio label='index1'/>
          <radio label='index2'/>
          <radio label='index3'/>
          <radio label='index4'/>
      </radiogroup>
      <button label="getSelectedIndex" onClick='Clients.log(rg1.getSelectedIndex());'/>
    </div>
</zk>

Current Result

Selected Index is not correct.

Expected Result

Selected Index is correct.

Debug Information

error occurs since ZK 8.5.1.

ZK-3818 cached _group  in onPageAttached() and remove _group in onPageDetached() in order to update selected index.   

_group should be cleaned before getRadiogroup() if the radiogroup changed.

Workaround

Add external radio after radiogroup rendered.