Ok, i gave a look to the code: actually categories includelet can show more than one category at a time if you pass a tree_name like "MyTree1 MyTree2". If you don't pass any tree_name, all mapped trees are shown.
I thought this includelet could show only one tree at a time! Now the presence of a separated "title" parameter makes sense. One could call it "Menu" for instance and let categories be shown, with tree name localized properly.
So far, so good. I then tried to understand how I could avoid to specify the locale to the includelet. I'd like it to understand that if it has been placed on a page in english, it should use the english locale.
In the code I couldn't find a way for the includelet to refer to the locale of its including page... I can use [ad_conn locale] or [::xo::cc locale], but this will return my language, not the one of the page... any suggestion?
