Jérôme Danthinne

Yep, have a look at https://github.com/PrestaShop/PrestaShop/blob/1.6/controllers/admin/AdminCategoriesController.php#L477, they're using a _tree_ index (but not documented).

What is your Prestashop version?

This is strange. I've developed the module using 1.6.0.13 as well. How did you install the module? What is the name of the folder you put in /modules?

Can you try the new version I've just pushed. It includes a .zip archive for easy install, and clear the caches on (un)install. Still working fine for me on a...

I can see the bug now. I've just tried to install the module on another hosted website and getting the same error… Still searching for the cause (thought it was...

Ok, it seems that this is working fine with PHP 5.5 but not 5.4. Trying to figure why.

No, not yet. If someone knows about 5.4 / 5.5 differences (in classes inheritance and overrides), he's welcome to have a look.

I've just tried that, but no change…

To clarify, what I mean by 'no change' is that the install process is ok now, but the renamed file is not installed as an override. So, pointless…

Can you try the latest version? I've made some commits that seem to fix the installation. I've managed to install the module with PHP 5.2.17.