I'm working with version 18.104.22.168 pro on a Mac Book Pro. I can browse the manual, but can't use the sidebar (the contents and index tabs show the information, but when I click, it refers to ...Downloads/qcad-22.214.171.124-1-demo.macosx.leopard.universal/doc/chapter04.html#absolute zero'). The path that it use is the original folder where I downloaded the demo program.
There is no "com.Qt Assistant.plist" file on my Mac as referred by the FAQ (http://www.ribbonsoft.com/qcad_doc_faq.html#15).
I couldn't find any way to change the path for the manual.
I have now all the QCad folders and files on my Applications folder.