Hi,
I can't recommend you change code in Form Runner, unless you really, really know what you are doing and you are ready to port those changes every time you upgrade, but assuming that is the case ;), I think you should be able to use controlOps:findControlByNameOrEmpty() to get access to the control, and then test on the value of appearance attribute, which should be "full" for radio buttons.
I hope this helps,
Alex
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