[Seaside] [Fix] Seaside-LangConfigPatch

[Bany, Michel]

> So, you are saying that we should subclass WASession each 
> time for each language?

I am not saying that. You can provide any computed value
for xml:lang in your #updateRoot: method. It does not
need to be a hard-coded constant.

As a matter of fact I was answering your initial question :
Yes, Seaside does allow you to change xml:lang and, more generally,
any attribute in the html element. The mechanism for that is to
subclass WASession and implement #updateRoot:

> I can not understand why subclassing is better...

With a configuration value, you simply assign a hard-coded value
to your application and you would probably need to define one
application for each language. IMO subclassing gives you more
flexibility.

Cheers,
Michel.