ajax listener does not fire when readonly is true

[giberius]

I am usering primefaces 2.2.1.

My code:

<p:column >
<h:inputText readonly="true">
<p:ajax event="focus" listener="#{schermitemBeanLijst.zetSelected}" update="details" onstart="alert('tom')" />
</h:inputText>
</p:column>

When I set my inputText with readonly="true" then my listener is not called anymore, I am quite sure the ajax event fires when I tested this with an alert and the details are rendedered. If I remove readonly (so that's the same as readonly=false) then the listener fires. I also tried immediate=true, this has no effect.

Is this a bug or intended behaviour?