"HHActiveX.DLL is an Adobe ActiveX control that provides support for online glossaries and browsesequences. Install and register the HHActiveX.DLL file on user systems. Copy this file from the appropriate location into the same folder as the CHM."
Do I have to give the developers this dll file in order for the chm to be displayed correctly?
You only need to provide this file if your CHM file is using the Glossary Tab function or the Browse Sequences function in the CHM files you create.
These features look like this in the compiled CHM (and when the proper DLL is registered and working:
Note that there are now actually two different versions of the Microsoft HTML Help viewer used to present the CHM file. One for 32 bit systems and one for 64 bit systems. As such, there are now two different versions of the HHACTIVEX.DLL file to distribute.
Again, this file is ONLY needed if you are using either of the two features mentioned. If you aren't, you are free to omit the DLL.