I'm not sure if this is already reported on Github, but theres a small bug in the unread tab that you can see hidden category's from the unread page. So I can see Area51 from that page without having permission to actually view category.
Thanks for reporting fixed in https://github.com/NodeBB/NodeBB/commit/0dfe2e0e90af19467982217b7220890e563d1e0c
Would love option to stop some categories from showing in this 'All categories' business.
If you have lots of categories they all show up 
Perhaps prevent "sub-categories" from showing in "All categories" - would be a nice easy way of hiding them from this !
If you ignore a category it won't show up in the dropdown.
@baris Ahhh the power of mouse drawn arrows, it would be nice to see a mass ignore button somewhere, to unsubscribe from all topics.
