I have get parameter with name controller. When I try to pass it (with propertyChangeListener) to my backing bean I get null instead of the real value of the parameter:

<h:commandButton value="#{msg['mail.send']}" styleClass="mailbutton" action="#{mailSender.sendMail}">
   <f:setPropertyActionListener target="#{mailSender.controllerName}" value="{#param.controller}"/>
</h:commandButton>

So, I have two questions:

1. What is the proper way to set bean property with a get-parameter value? Actually, I've already get the value from ExternalContext#getRequestParam but maybe there are some other solutions.
2. More interesting question: why propertyActionListener didn't work here? What does it do actually? (again I have some thoughts about it but it would be nice to read more comprehensive explanations).