[Ur] Radio button default values

[Adam Chlipala]

Taru Karttunen wrote:
> Is it possible to set a default value for a radio button group
> (radio/radioOption) without checking any option? I'd like to avoid a
> nasty error page when a form is submitted without any of the radio
> buttons checked.
>    

Your question leads me to realize that, as far as I can remember, I've 
only ever used radio buttons in Ur/Web via one small test program. :)  
So it's not surprising if the interface has some deficiencies.

What would you think about changing the type of a <radio> widget from 
[string] to [option string] (so [None] can be the default value)?  Does 
anyone else have an opinion on this?