[Seaside] Seaside updater

[Lukas Renggli]

> I looked at the SUFormTest code. It took me into the guts of WARenderCanvas
>  and WARenderContext where I got totally lost. All this stuff about 'context'
>  and 'nextKey' and so on is so convoluted. For anyone but a Seaside expert,
>  this would be unfathomably difficult to use without clear documentation and
>  simple examples.

I guess, what you want to do has absolutely nothing to do with
#nextKey. This is just used to create an unique id (as its comment
says).

>  A few HowTo's at seaside.st would be very helpful for the rest of us... How
>  To use #updater, for example (since #updater is a major aspect of Seaside
>  programming).

To trigger a callback of a form elment, you need to specify this form
element with #triggerFormElement:. As the comment of this method says,
this does not work for multi-select lists and checkboxes, as those two
form elements internally depend on another hidden form element. So
four your checkbox you need to trigger the whole form. Give it an
(unique) id and use #triggerForm: with this id.

Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch