Using id change a bit the behaviour and can bring new small ambiguities :
- If the web developer create manually a fieldset containing one of the class ('right', 'left'), the javascript will try to create the table containing the fieldset
- if the web developer create a fieldset with name 'center_left' and an extra class 'right'  (using parenthesis in the group name), the javascript will position the fieldset on the right side.
This cases should be very rare (second one is like a mistake). This problem could be avoided by changing template and css to not use javasacript to position elements (I think that this could be made using pure HTML + CSS).

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34799 20353a03-c40f-0410-a6d1-a30d3c3de9de