Hi Marc,
This is a good question. But as it happens, now I have an answer to it.
The old help file seems to have a set of Quick Info popup window data that belongs to topics which didn't make it into that particular file and have no mention (cross-reference) in either the help contents tree or any other topic included in the file. Such topics obviously were Microsoft's legacy OpenGL 1.1 software renderer driver, deprecated early DirectX interfaces, and probably a few others.
All the missing files that I found have a
__QI suffix in them. The keywords they belong to have no cross-reference to any other topic in the file, cannot be found by extended search in either the .HLP or .CHM version, and for all intents and purposes are
dead data.
(See an example in the attached snapshot)On default, MS HTML Help Workshop ignores the files that have not a single cross-reference elsewhere in the project (starting from the contents tree) and compiles them into the resultant .CHM only if explicitly forced to do so; there's a dedicated
[FILES] option in the .HHP project file for this purpose.
I didn't find any information in these files that may be of interest or help to a casual user in the year of 2015. Therefore, I didn't enforce MS HTML Help Workshop to include any dead data into the resultant .CHM file this time, while my older compilation contained a [FILES] section of all the 16K topics found in the decompiled 50MB .RTF content file.
So, in my opinion it would be reasonable to dismiss this matter as it is really not an issue. There's no real reason in storing the dead data that you wouldn't be able to access, and especially so if the said data is of very questionable value at present times.
Anyway, thanks for bringing this matter to my attention. I hope you're satisfied with my findings.
.