[Seaside] Usage of Canvas' #select and #labels

[Rick Flower]

Philippe Marschall wrote:
> html select
>    beOptional
>    list: orgs;
>    on: #orgId of: self;
>    labels: [:org | org name ];
>    optionalLabel: 'Select One...'.
>
Well.. This works fine for regular times when using regular callbacks 
but fails when using a liveCallback (care of SeasideAsync) as the index 
is off by 1.. I'll see about making a fix to do the right thing when I'm 
a bit less tired..  I guess we need to teach it about the use of 
beOptional and friends.  Once that is done then it should work ok.