nixos: fix cursor size

cursor.md

Fix cursor size in nixos/linux

1. Set your XCURSOR_SIZE to 32 (or desired size) in either your /etc/nixos/configuration.nix

environment.variables.XCURSOR_SIZE = "32";

or ~/.Xresources:

Xcursor.size: 32

2. in ~/.Xresources, set the theme to Adwaita. (You'd want the gnome3.adwaita-icon-theme nix package installed.)

Xcursor.theme: Adwaita

3. in ~/.gtkrc-2.0 set the following:

gtk-cursor-theme-name="Adwaita"
gtk-cursor-theme-size=32

4. in ~/.config/gtk-3.0/settings.ini set the following:

gtk-cursor-theme-name=Adwaita
gtk-cursor-theme-size=32

5. Logout and log back in. (If you changed /etc/nixos/configuration.nix do a sudo nix-rebuild switch and reboot.)

Change the size and theme as desired -- just make sure that the settings in the above files are in sync.

@themattchan you suggestions mostly worked for me, but only after I installed the icons from the following package.

gnome3.adwaita-icon-theme

Everything worked after this, thanks for taking the time to document the fix.

To others who are frustrated none of these settings work, it's probably because you don't have an icon theme to use installed. Especially if you're and i3 user.

@themattchan Thanks for documenting this!

When I stopped using a desktop environment, I started getting a big old "X" cursor in some contexts (e.g. hovering over a zoomable image in chrome), even though I had set my default XCursor to the left pointer. The only other documentation/examples I found were in the context of home-manager, which I don't use.

Your suggestions fixed the issue and taught me a little more about how cursor themes are managed.

If using Home Manager, then this is encapsulated by e.g.

{ pkgs, ... }: {
  xsession.pointerCursor = {
    name = "Adwaita";
    package = pkgs.gnome.adwaita-icon-theme;
    size = 32;
  };
}

Despite being "xsession", Wayland desktops benefit from some of what this does as well.

I got the notification that xsession.pointerCursor is being deprecated, and I found the new option here https://nix-community.github.io/home-manager/options.xhtml#opt-home.pointerCursor
Hope this helps :)