Ability to lock certain static categories behind a secondary password
Let's say that the end user has some books stored in LR that they wouldn't want other viewers to accidentally stumble upon, and they have these books specifically categorized in another category. (Such an example would be if someone uses LR to store a large amount of non R18 stuff, but there's also very few R18 books mixed in there - and while they would like anyone to be able to freely access the SFW collection, the NSFW stuff would be preferred to kept private.)
This would bring in the need of a secondary password protection - as in the ability to lock certain static categories behind a password different from the Admin password, so that it is ensured that nobody would accidentally stumble upon something that isn't appropriate to view.
Meanwhile, archives in "locked" categories would also be excluded from the "random archive" button at the bottom of the reader, just to ensure that they are completely secure.

Doesn't sound that hard to implement, so I thought I'd drop this idea here.
I've been thinking about adding a secondary password for only reading/uploading for #630 and #740, but I don't think I'd go as far as also tossing password-only archives in there for the time being.
Maybe for later though!