Cannot grab correct UID from hook

[Shade]

If you are hooking into datahandler_login_complete_end, the $mybb->user object is still stuck to a general guest data. The user data will be loaded afterwards, so you should grab the authenticated user data by using the argument passed in the hook, which is a "by-reference" hook type:

function myplugin_datahandler_login_complete_end($user)
{
  global $session;

  setcookie('my_session', $user['uid'] . ' ABCDE ' . $session->sid, time() + (86400 * 30), "/");    
}