Ask HN: What are some examples of great GUI tool docs?

HyperCard comes right to mind, although it's been at least 20 years since I saw the documentation. http://hypercard.org/ has screenshots of one of the on-screen documentation files (click HyperTalk Reference), itself a HyperCard stack.

Here's the original manual (PDF from Apple): http://download.info.apple.com/Apple_Support_Area/Manuals/so...

What I can't find is the "Hypercard Tour" referenced there.

For Mac, Dash is great: https://kapeli.com/dash

It even integrates with Alfred so you can search directly from there with one keyboard shortcut.

qt.io is the best