Wrote a blogpost about simple (I mean with a shell and a text editor) #X11 configuration.
Covered topics:
1) #Trackball configuration for left hand. Also remapping of some buttons to have scrolling and middle button (not exists out of the box).
2) Theming: #GTK2 #GTK3 #QT , installing cursor(s), fonts and icons.
3) #Xrandr for multimonitor configuration
4) #Xserver settings for #HighDPI
5) #XDG utils and #Emacs as a system file manager
6) #XDM login window
https://eugene-andrienko.com/en/it/2025/07/24/x11-configuration-simple.html