I see no problem in having invalid font dirs in class var. The paths
just need to be checked when image starts. why this a problem?
If going this way, you can just put there all well known paths for
every known platform at package installation phase and don't care if
they all valid. Rendering engine must be aware that some or all of
given directories can be missing or contain no fonts. You need to
check it anyways because they external to image and if i added new
directory and then moved/renamed it in my OS the squeak must not crash
after restart.