On 21 Jul 2008, at 12:09, Dan Nicolaescu wrote:
>>
>> + ;; Show-newlines-mode
>> + (defface blank-newline
>     +  :group 'blank)
>       ^^^^^^
> This group does not exist.

Actually, how about `whitespace' (like the other whitespace  
customizations) for the face and the two minor modes?
That's more specific than `display'.