Qt seems to have succumbed to the CMake plague. GTK is evil but the rot is just present in general in all modern software nowadays (shoutouts to the fuckwad that took over stalonetray, and decided that it needed fucking meson and C23 of all things. For an ostensibly simple standalone X11 tray program)

For non-garbage programs and GUI operation, you're probably better served with anything that's "pure" X11 or uses a not-yet-totally-enshittified toolkit like Motif as opposed to GTK or Qt (there where there's such programs available, of course)