<zk>
<vbox>
<listbox width="300px">
<listhead sizable="true">
<listheader align="center" width="40px" label="xxs" />
<listheader align="center" width="40px" label="xxs" />
<listheader align="center" width="40px" label="xxs" />
<listheader label="Subject" />
<listheader label="Received" />
</listhead>
</listbox>
<button label="blue"
onClick='org.zkoss.lang.Library.setProperty("org.zkoss.theme.preferred", "classicblue");
Executions.sendRedirect(null);' />
<button label="breeze"
onClick='org.zkoss.lang.Library.setProperty("org.zkoss.theme.preferred", "breeze");
Executions.sendRedirect(null);' />
</vbox>
</zk>