some more facts :the described behavior only happens inside a datatable. the same construct outside the table, everything runs fine.
<t:dataTable [...] >
[...]
<h:column>
<f:facet name="header">
<t:commandSortHeader
columnName="timestamp"
arrow="false">
[...]
</t:commandSortHeader>
</f:facet>
<h:outputText value="#{msg.timestamp}" >
<f:convertDateTime
type="both"
dateStyle="medium"
timeStyle="full"
timeZone="#{config.timeZone}" />
</h:outputText>
</h:column>
</t:dataTable>
regards
Ronald

