Altri test:

la scritta incriminata è:
codice:
<h:panelGroup binding="#{calculatorController.resultsPanel}" rendered="false">
<h4>Results</h4>
	   <h:panelGrid columns="1" rowClasses="oddRow, evenRow"
	    styleClass="resultGrid">
	    <h:outputText value="First Number  #{calculatorController.calculator.firstNumber}"/>
	    <h:outputText value="Second Number #{calculatorController.calculator.secondNumber}"/>
	    <h:outputText value="Result  #{calculatorController.calculator.result}"/>
	   </h:panelGrid>
  	</h:panelGroup>
Se io lascio solo:
codice:
<h4>Results</h4>
	   <h:panelGrid columns="1" rowClasses="oddRow, evenRow"
	    styleClass="resultGrid">
	    <h:outputText value="First Number  #{calculatorController.calculator.firstNumber}"/>
	    <h:outputText value="Second Number #{calculatorController.calculator.secondNumber}"/>
	    <h:outputText value="Result  #{calculatorController.calculator.result}"/>
	   </h:panelGrid>
si spacca, se invece lascio solo:
codice:
<h:panelGroup binding="#{calculatorController.resultsPanel}" rendered="false">

</h:panelGroup>
non mi da errori!

Per qualche motivo a me oscuro con quel binding non mi genera errori quando chiamo il metodo..
Ma non riesco a capire perchè!!