While creating a theme and looking for not correctly styled elements I came across "some" not functional links and buttons in Compdoc.
This module seems not to be finished or working properly, because most of the times, the buttons inside the appbar produce errors or just empty pages.
Even when searching for existing elements and then clicking on them to examine or edit them will mostly create an error (example: go to compdoc, search for template child, click edit on some random found element -> error).
Sometimes the menu which is included inside the appbar, mostly the menu called "tree", need the contentId for the buttons to work.
Including this menu while creating a new entry will result in every button not working and throwing an error, except the edit button, which will produce a completely empty page.
Those things appear all over the module, trying some button or clicking some link resulted in an error screen more than it resulted in something actually working.
This should either be fixed or removed, if this doesn't has a real purpose at all.