When you put AJAX behavior on component with setRenderBodyOnly(true) and try to call it with callback script it won't get called and no error / warning is displayed. See attached quickstart sample. Just unzipp and run with: mvn jetty:run
Navigate browser to http://localhost:8080/
When you try to click on labels AJAX behavior should get called. But it won't. This kind of behavior is correct (i assume). But i think user should be warned that behavior can't be called. I think proper place is somewhere on server side? But I don't know where exactly put the warning.