Primeface requiredMessage in a Dialog. Keep in Mind the own <h:form> Tag

requiredMessage.xhtml

<h:form>
	<p:commandButton value="open dialog" id="btncallWidget" process="@this" oncomplete="PF('editDlg').show()"/>
</h:form>

<p:dialog id="editDialog" header="Dialog" widgetVar="editDlg" modal="true" appendToBody="true">
	<p:tooltip />
	<h:form>	
		<p:growl id="growl" showDetail="true" sticky="false" />  
		<h:panelGrid id="grid" cellpadding="5" columns="3" style="margin-bottom:10px">
			<f:facet name="header">
				 <p:messages id="msgs" showDetail="true" autoUpdate="true"/>
			</f:facet>

			<p:outputLabel for="firstname" value="Firstname:" />
			<p:inputText id="firstname" value="" />
			<p:spacer/>

			<p:outputLabel for="surname" value="Surname:" />
			<p:inputText id="surname" value="" required="true" requiredMessage="Surname is required." />
			<p:spacer/>

			<p:outputLabel for="tt" value="Tooltip:" />
			<p:inputText id="tt" required="true" />
			<p:message for="tt" display="tooltip" />

			<p:outputLabel for="txt" value="Text:" />
			<p:inputText id="txt" required="true" />
			<p:message for="txt" display="text" />
		</h:panelGrid>
		<p:commandButton value="Form" id="btnForm" process="@form" update="grid growl" />
	</h:form>
</p:dialog>