(http://markmail.org/message/3bietj36wvz6h3dz, where Chris Lewis is pondering a way to implement a confirm mixin). Based on that and browsing ck.button source, I'd say the most proper solution is not to use ck.button in a case like this, but a plain html button with onclick confirm and wrap it in action/event link. Of course, Chenillekit could re-implement the ck.button to render the same but not so convinced it'd be worth it.