WrongValueException message is disappearing...

According to this threads - http://www.zkoss.org/forum/index.zul#path%3DlistComment%3BdiscussionId%3D6147%3BcategoryId%3D14%3B

For example,

<zk>

<zscript><![CDATA[

String[] data = new String[200];
for(int j=0; j < data.length; ++j) {
data[j] = "option "+j;
}
ListModel strset = new SimpleListModel(data);

void test() {
uiDecimalbox.focus();
uiDecimalbox.getValue();

} ]]>
</zscript>
<window title="Test Wrong Value Exception" border="normal" width="1200px" height="600px">
Please scroll down to press the submit button, than you should see the Warning box.
<panel style="margin-left:10px" width="800px" height="500px"
title="TEST PANEL"
border="normal" visible="true">
<panelchildren
style='background:white;background:white;overflow:auto;'>

<decimalbox id="uiDecimalbox" constraint="no empty" />
<listbox model="${strset}" width="200px">
<listhead>
<listheader label="TEST ITEMS" sort="auto"/>
</listhead>
</listbox>
<button label="submit" onClick="test()"/>
</panelchildren>
</panel>

</window>
</zk>