<zk>
    <grid>
<!--        <custom-attributes org.zkoss.zul.css.flex="false"/>-->
        <auxhead>
            <auxheader label="aux1"/>
            <auxheader label="aux2"/>
            <auxheader label="aux3"/>
        </auxhead>
        <columns>
            <column label="col1" hflex="1"/>
            <column label="col2" hflex="2"/>
            <column label="col3" hflex="1"/>
        </columns>
    </grid>
</zk>