Answered
According the reference guide allowNeutral specifies whether the check box or radio button can support an additional third state that represents a
neutral value.
I have tried to set this value using javascript and edited the xdp directly to set it, however no luck.
What we are trying to achieve is to allow a user to deselect a radio button set once they have selected an option.
Has anybody successfully used this feature?
Yes, you can do this. I just created a test form and it works fine.
Create a new test form. Add a radio button. Set it's name to "rbTest". Copy and paste this button to create "rbTest[1]". Rename the radio button container group to rTest. Create a button labelled "Get Value". Create another button labelled "Reset Selection". Create a text label, named "tTest".
You now have, in the Hierarchy pane:
Form
-rTest
--rbTest[0]
--rbTest[1]
-Button1 "Get Value"
-Button2 "Reset Selection"
-tTest "Text"
Add some code:
Button1::click gets:
tTest.rawValue = Str(rTest.rawValue)
Button2::click gets:
rTest.rawValue = 0
Save your form and then click the "Preview PDF" tab and play with selecting and reseting your radio buttons.
Enjoy!