[Seaside] callbacks of disabled submit buttons

[Sebastian Sastre]

Hi there,
fact: when you disable a submit button it's not going to be serialized.
problem: you want to disable the button after the click but you also want to
execute its callback.

This is often needed. For instance a login form. You want the user to login and
wait for the result. The disable of the button is just to make it idempotent
until the result is received preventing silly server load.
Another example is a "confirm purchase" kind of button where a capture of money
is made.

Any ideas?

sebastian