I still think the root of the problem here is that the "zoom" xscreensaver hack is marked as enabled in the .ad file, but it is not actually installed. So the .ad file is wrong. Correcting it would fix this. I suppose it would be possible to do that in a post-install script on the xscreensaver sub-packages.
It would also work to make every entry in the .ad file be an absolute path instead of relative. But I don't like the idea of forcing entries in the .ad file that are not absolute paths to only run from a hardcoded directory. -- Jamie Zawinski https://www.jwz.org/ https://www.dnalounge.com/