Look for bugs and usability problems

[Dawoodoz]

If anything seems out of the ordinary, investigate and file an issue. Even if you are technically wrong about something, you first assumption is important for improving the library's usability. It's the documentation's fault if you read it and still made a mistake.

I'm making this into an explicit task because it's easy to forget the importance of things that cannot be measured when checking things off on a long list. Quality is what matters most.

[Dawoodoz]

Changed Hidden to Visible, because it felt unconventional when I started to use it.