Steps to Reproduce

1. run the zul

   <zk>
    <label multiline="true">
      1. check 1st item
      2. check last item
      3. uncheck last item
      Actual Result:
      auto scroll back to 1st item
     </label>
   		<listbox height="300px" checkmark="true" multiple="true">
   			<listitem label="John" />
   			<listitem label="MALE" />
   			<listitem label="20" />
   			<listitem label="A college student." />
   			<listitem label="John" />
   			<listitem label="MALE" />
   			<listitem label="20" />
   			<listitem label="A college student." />
   			<listitem label="John" />
   			<listitem label="MALE" />
   			<listitem label="20" />
   			<listitem label="A college student." />
   			<listitem label="Mary" />
   			<listitem label="FEMALE" />
   			<listitem label="18" />
   			<listitem label="A young lady." />
   			<listitem label="Mary" />
   			<listitem label="FEMALE" />
   			<listitem label="18" />
   			<listitem label="A young lady." />
   			<listitem label="Mary" />
   			<listitem label="FEMALE" />
   			<listitem label="18" />
   			<listitem label="A young lady." />
   		</listbox>
   </zk>
   

2. check 1st item
3. check last item
4. uncheck last item

Actual Result

Listbox auto scrolls back to 1st item.

Expected Result

No scrolling happens.

Debug Information

SelectWidget._toggleSelect(), this._focus(closestSelItem);