It appears the 'v' switch has no effect in combo with the 'e' switch. I can't get there to be any difference in clicking with an empty editbox on yes/no/cancel:

//echo -a $input(test,evn)

I dunno if that's 'by design' or something that could be added by a feature request. Obviously there's no reason for the 'yes' button to return $true when there's an editbox, but there could be use cases where clicking on no or cancel would behave the same as if typing $false or $cancel into the editbox then clicking yes.

But also, in your example you're using the double dollar, so that's going to halt rather than setting %x to null.