Having s:convertDateTime for param in .page.xml seems to cause s:button to loose value for that param.
If I remove s:convertDateTime from param, then clicking s:button, below' maintains the value for that param.

Seam 1.2.1GA

.xhtml
<s:button view="/report/application-stat.xhtml" value="Back" action="#{applicationStat.submitSearchAction}"></s:button>


.page.xml
<page login-required="true" action="#{applicationStat.pageAction}">
...
 <param name="from"/>
 <param name="executeSearch" value="#{applicationStat.executeSearch}"/>
 <param name="printable" value="#{applicationStat.printable}"/>
 <param name="applicationDateFrom" value="#{applicationStat.applicationDateFrom}" converter="#{s:convertDateTime}"/>
 <param name="applicationDateTo" value="#{applicationStat.applicationDateTo}" converter="#{s:convertDateTime}"/>
 <param name="applicationDateLate" value="#{applicationStat.applicationDateLate}" converter="#{s:convertDateTime}"/>
</page>