Can I use a radiobutton to fill a checkbox?

Setting a checkbox via a GuiXT radiobutton is not yet supported. It is a good idea and we will add it to our list for further development.

With the current GuiXT version, the only way would be to use a radiobutton that is connected to an internal variable (see documentation, Radiobutton (IA)), and to set the checkbox in the InputScript (before the first Screen command in the InputScript).

This works fine if you can assure that the InputScript is performed in each relevant case. Use "On" commands, and/or a pushbutton.