I'm absolutely new to osclass. I must say, the first impressions are better than great.
First I added two more languages then removed the English.
Just started to add some categories, but when started editing, the default language tab was always the secondary language.
After a brief research, I modified the code @ oc-includes/osclass/frm/Category.form.class.php
line 113: insert line $tabs = array_reverse($tabs);
This solved my problem.
I don't know, this is an issue, or just depends on the order of languages added. But anyway, there must be a check in the code to prioritize the default language...
BTW the best project I ever seen! Thanks!