xscreensaver-demo makes it sound fairly unimportant, but -demo is how you launch the configuration GUI and select screensavers, turn on settings like when to lock, etc. For example, in XFCE, I went to click on the menus to select "screensaver" and it said xscreensaver-demo was missing. I imagine this could be confusing. It confused me.
Looks like we're not the only ones hitting this issue: https://bugs.gentoo.org/753905 Tobias Geerinckx-Rice <m...@tobias.gr> writes: > Hi Christine, > > Note that the name of this tool has changed upstream[0], but we're > still on an older version for now. Building it: > > Warning: GTK version 2.24.33 was found, but at least one supporting > library (gdk-pixbuf-xlib-2.0) was not, so GTK can't be > used. > Perhaps some of the development packages are not installed? > > Warning: The GTK libraries do not seem to be available; the > `xscreensaver-demo' program requires them. > > Where gdk-pixbuf-xlib is of course ‘a deprecated library’ and ‘[n]o > newly written code should ever use this library’ so that'll be fun to > maintain the coming years. > > Our gdk-pixbuf package still mentions gdk-pixbuf-xlib-2.0.pc in an > obsolete comment but doesn't actually install it. > > Oh: > > NEWS: - Split the gdk-pixbuf-xlib library to a separate repository > > The repository is archived and read-only: > > https://gitlab.gnome.org/Archive/gdk-pixbuf-xlib > > Oh that is going to be *super* fun to maintain. > > At this point I'd usually go ahead and package the beast, but I don't > use xscreensaver. How important is this binary? (-demo sounds > unimportant, -settings very, but it's presumably the same thing.) > > In any case an update to xscreensaver would seem prudent first. > > Kind regards, > > T G-R > > Sent from a Web browser. Excuse or enjoy my brevity. > > [0]: https://www.jwz.org/xscreensaver/changelog.html