test:set-radio-box!

• (test:set-radio-box! radio-box state) -> void
      radio-box : (union (instance radio-box%) string)
      state : boolean

  Clears the radio-box% item if state is #f, and sets it otherwise.

  If check-box is a string, this function searches for a radio-box% with a label matching that string, otherwise it uses radio-box itself.