tl;dr: A useful hypertext toolbox reference in the spirit of THINK Reference but newer and first-party. Got it off eBay recently. Now on the garden. People don't seem to know it exists. Worth a try, but it's no THINK Reference. More details below.
Macintosh Programmer's Toolbox Assistant is a hypertext reference tool for the Macintosh OS and Toolbox, essentially an offline hypertext version of Inside Macintosh. The classic tool in this genre is of course THINK Reference, but by 1995 THINK Reference had been discontinued for a good while. I don't know if this tool was designed intentionally to fill that gap, but in effect, that is what it does (though not entirely successfully...)
I found this on eBay UK a few months ago (it may actually have been a @joshc find, I can't quite remember). I hadn't heard of it, and it didn't seem to have been archived/made available anywhere I could find, so I picked it up.
It installs off CD, and when it opens, it is just to an alphabetical list of routines. This is the default, although one can browse by manager as well as with a full-text search.
Overall, the information presentation is slightly better than THINK Reference's: it uses different sizes of text and background colours to highlight different parts of the page fairly effectively, and simpler types pop up in tip-like popups rather than having a whole separate page (though I do wish these popups contained more information, or onward hyperlinks where appropriate...)
You can also add stickies to pages yourself by dragging the yellow sticky note from the toolbar onto the page. These notes remain there, anchored to that place on the page, until you explicitly delete them, which is a feature that TR doesn't have. You can turn on and off the viewing of sticky notes.
The text itself is very close to the reference sections of IM, as far as I can see: certainly very much in the same style. And this is where it can't really compare to THINK Reference, because part of the usefulness of TR was that it was a supplementary text, written by different people partly as a reaction to IM. Where IM was unclear, TR could be clear, and vice versa. Of course, this IM-lite doesn't have the same kind of relationship with its parent text, and this is a loss.
Here, for comparison, is the documentation for ADBOp in both THINK Reference and the Toolbox Assistant. I find the page layout in Toolbox Assistant much clearer for its use of colour and whitespace and page structure (for example, the "DESCRIPTION" header), and it's obviously less imagined on a black and white compact screen (which may or may not be a good thing).
But even in this largely arbitrary example, you can see elements where THINK Reference is noticeably clearer about what the call expects of its caller than Toolbox Assistant is, especially in explaining what the parameters are for (though, like Homer, itself nods occasionally; a ProcPtr isn't a structure).
And finally, Toolbox Assistant feels rushed: and you get a bit of a feel for that fairly often:
I've ended up with both installed, personally, in much the same way as I would compare TR and IM, and I've found this reasonably useful. But I'm interested to hear from other people—has anyone else come across this tool before? What did you think, if you did? What do you think now, if this is the first time you've seen it?