Thanks, I fixed this in another place. See c32f0674ace8.

I think we'd need a change around https://git.kolab.org/diffusion/C/browse/master/lib/api/common.php$237, but I didn't think about it yet.

That scenario is not supported because you can't store config and you can't use cache without kolab backend. You could probably live without these in some setups, so yes in theory it should work. There must be a bug somewhere.

... and we should throw an error when fileapi_backend != 'kolab'.

I think we should finally remove that section from documentation. It is not supported scenario, I think it is not even supposed to work. There's a comment in sample config:

// Main files source, backend driver which handles
// authentication and configuration of Chwala
// Note: Currently only 'kolab' is supported
$config['fileapi_backend'] = 'kolab';

Yes, kolab_files uses now different (semi-recurrent) logic to fetch folders hierarchy. How exactly did you configure chwala with seafile?

That's a bug introduced by e544905221b and the fix makes sense.

@bohlender, would you make a summary in English for me, or should I just ignore all comments?

Check Roundcube error log. It might be caused by invalid/missing timezone setting in php.ini.