I spend the whole day trying to find a solution.
I have a rather common case...a dataTable with input fields
and a button to add a new row.
What happens is that the row is added, but the text in the
input field is empty. How can I keep the value?

<a4j:region>
 <rich:dataTable var="data" value="#{invoice.itemList}"
id="itemTable"
 rowKeyVar="rowIndex" binding="#{invoice.dataTable}">

 <f:facet name="header">
 <h:outputText value="#{msg.invoiceItem_table_header}" />
 </f:facet>

 <rich:column width="18px" sortable="false">
 <f:facet name="header">
 <rich:spacer />
 </f:facet>
 <a4j:commandButton id="delete" actionListener="#{invoice.deleteLine}"
 image="/app/images/delete.gif" alt="#{msg.global_button_alt_delete}"
 reRender="itemTable" immediate="true" rendered="#{rowIndex > 0}"
 ajaxSingle="false" >
 <f:param id="rowIndexDeleteId" name="rowIndex" value="#{rowIndex}" />
 </a4j:commandButton>
 <rich:spacer />
 </rich:column>

 <rich:column>
 <f:facet name="header">
 <h:outputText value="#{msg.invoiceItem_text}" />
 </f:facet>
 <h:inputTextarea value="#{data.text}"
 binding="#{invoice.inputText}">
 </h:inputTextarea>
 </rich:column>

</rich:dataTable>
</a4j:region>