Found solution:
I detect the prefered language from the visitor:
-I take only the first two characters (en-us -> En; fr-ca -> Fr;)
-If other than Fr, De, En, then it's En is used
-I set the menulang = menuXx.txt directly in monobook.php
-I set the menulangPage = menuXx directly in monobook.php
1) use the haveData function from skinTemplate.php instead of text:
<?php include($this->haveData('menulang')) ?>
2) use a page from your MediaWiki namespace as a navigation menu: the
function to use is msghtml
<h5 >Menu:<?php $this->text('menulang') ?></h5>
<div class="pBody">
<ul id="t-menu"><?php $this->msgHtml($menulangPage) ?>
</ul>
</div>
Does anybody knows if there is a simpler way of doing this. I 've heard
a lot of interwiki language, is it applied to change the interface from
visitor to visitor?
Thanks a lot
François