This works in regular FileMaker, maybe it will in IWP: click the radio button field to give it the focus and then press the delete key.
good idea, but nope, that doesn't work either
You could add one more value to your value list with a single space or text such as <clear>.
Then an auto-enter calculation can clear the field when that's the value of the field:
If ( self = " " ; "" ; Self )
If ( Self = "<clear>" ; "" ; Self )
and clear the "do not replace existing values..." option.
Main draw back is you won't see the field actually clear until the data is submitted so it may not be sufficiently responsive for what you need.
another good idea! but yeah, already have a LOT of layout done, everything would have to move to add a third option to every radiobutton set.
I guess I'm just going to add little blue buttons that setfield to "" when clicked. I can make the buttons small enough to drop in without disrupting the layout.
(and I'm off to update a whole bunch of target field names on copy and pasted blue buttons)
(In fairness to FM Help, it does point out that radio buttons cannot be cleared in IWP by conventional methods. They suggest you have a 'Clear' script button, from memory.)