However, I have been able to recover use of my .HLP files by following the advice given in the site whose address I attach. The usual caveats about security apply, as the writer of the advice points out.
By using the Method 1 described there, even F1 help works.
I hope this helps.
As you realise WinHelp is really old and has a number of security vulnerabilities. You have to jump through increasing higher hoop to get it to work on systems after Windows XP. Given the base data is RTF which opens in Word there are a number of not two difficult things you can do. For example you can convert it to a pdf with a hyperlinked table of contents. You can make it into a series of html files with and index page or indeed you could pack the html into .chm (HTML help) all of those work and are supported.
1) links to how to convert to what you recommend would be appreciated though, and
2) whatever file it becomes, can it be used in the following way from within a Windows dialog application with minimal disruption to app visibilty:
if ( WinHelp (dlg%hWnd, lpszHelpFilename, HELP_FINDER, OL) .EQ. 0) then.....
If not, I will try and stick with WinHelp.
You can still use the old help. All you need is a copy of winhlp32.exe from an XP system.
to install it, here is a long-running thread regarding this issue:
Doc (not an Intel employee or contractor)
[Windows 11 is the new Vista]
On the original topic the htmlhelp Api is very similar to the old winhelp api. It is just the technology for viewing and storing the help data is changed. If you use the .chm format ( a html files wrapper) you use Help Workshop to make teh chm file from youd html file sources. You can get html workshop as a downloaded from MS (or is bundled in the windows SDK stuff also).
HWND HtmlHelpA( [in, optional] HWND hwndCaller, [in] LPCSTR pszFile, [in] UINT uCommand, [in] DWORD_PTR dwData );