The entire Grid is invalidated when adjusting models and a couple of components

It seems that the entire Grid is invalidated when reloading data. This is not an MVVM issue, as it happens on the current demo also which makes use of EL.

As a side effect to this the cursor in the textbox is set to the beginning. This causes a bad flow when trying to filter.

I have attached a fully working sample of the issue, the sample uses maven and you can run it straight away.

Here is the simplified code to replicate the issue. Type something and wait. Then, you'll see the textbox's content is cleared (which is wrong).

<zk>
<zscript>
import org.zkoss.zktest.test2.select.models.*;
ListModel model = ListModelArrays.getModel(ListModelArrays.DEFAULT);
</zscript>
<grid id="grid" model="${model}">
    <columns>
        <column label="Category"/>
    </columns>
    <auxhead>
    	<auxheader>
    		<textbox onChanging="grid.setModel(ListModelArrays.getModel(ListModelArrays.DEFAULT))"/>
    	</auxheader>
    </auxhead>
</grid>
</zk>