There is an exception on Tomcat6 when testing the ace:ajax listener for the maskedEntry event 'keypress'. The exception can be fixed by changing the method argument from 'KeyPressEvent' to 'AjaxBehaviorEvent', and it does not occur on Tomcat7 when using the KeyPressEvent as the argument (as listed in the tlddoc).

WARNING: /maskedEntryAjax.xhtml @86,99 listener="#{ajaxTestBean.keyPressEventListener}": Method not found: org.icefaces.maskedEntry.AjaxTestBean@e20ef8.keyPressEventListener(javax.faces.event.AjaxBehaviorEvent)
        javax.el.MethodNotFoundException: /maskedEntryAjax.xhtml @86,99 listener="#{ajaxTestBean.keyPressEventListener}": Method not found: org.icefaces.maskedEntry.AjaxTestBean@e20ef8.keyPressEventListener(javax.faces.event.AjaxBehaviorEvent)
            at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:109)
            at org.icefaces.ace.component.ajax.AjaxBehaviorListenerImpl.processAjaxBehavior(AjaxBehaviorListenerImpl.java:82)
            at javax.faces.event.AjaxBehaviorEvent.processListener(AjaxBehaviorEvent.java:113
    .............

Test app located here: http://server.ice:8888/svn/repo/qa/trunk/Regression-Icefaces2/Sparkle/Nightly/maskedEntry