So after leaving neon to use a newer ubuntu (needed it for my hardware), I have started building KDE myself again and tried setting my tradition install in /opt and building with kdesrc-build.
I ran into a number of issues, many minor things I have already fixed by patches. But there were two bigger issues with dbus-1 and polkit. First kscreen doesn't work because it can't find its backends. While not easily found, I did eventually find suggestions online to fix this by adding a file in /etc/dbus-1/session.d with the prefix service dir. I talked to the dbus people and they seemed positive about automatically using XDG env variables to do that automatically in the future, but currently you still need to add that file. Perhaps kdesrc-build could document that and maybe have a sudo install mode that installs that? The second issue was that powerdevil brighness controls didn't work. This was because of something similar with the actions and services not installed for polkit-1, this is a bit more complicated as polkit-1 does not allow you to add extra prefix directories. So you need to add the actions in /usr/share/ polkit-1/actions. And those files you need to install are not even generated. I have tracked it down abit and found that kauth actually has a tool to generate the action files and have a cmake command kauth_install_actions that is even used by powerdevil, but the .policy files are still not generated nor installed in prefix or /usr/share by kdesrc-build. Anyone know why this is? 'Allan