Cannot cancel ck.button with Javascript confirm() - server-side event if fired in any case

Discussed on user list, see http://markmail.org/message/stetk3okychsrpia
"I can add an onclick handler but the button is just registered to listen to a click event so it'll fire a server-side event anyway regardless of the confirm dialog action."
Massimo says:
"Well, I've implemented this as a mixin in one of my projects and the
current feature of @BindParameter helps a lot here so please add a
JIra issue and i'll take care of that with more discussion happening
there."

Current workaround is to add confirm() in a nested element and stop event propagation there.