linux: wrong mouse cursor size on multi-monitor setup

[HE7086]

I have a kind of cursed display setup:
Display 1: 3840x2160 @ 150%
Display 2: 3840x2160 @ 200%
Display 3: 1920x1080 @ 100%

Ghostty is handling the cursor size incorrectly on 1 and 2.
The recording attached is at the connecting edge of 1(left) and 3(right).
All other applications are working properly.
I have tried to set all 3 displays to 100% scale and the problem is resolved.

System information:
WM: Kwin wayland (KDE Plasma 6.2.4)
Cursor: Breeze_Light (36px)
GPU: NVIDIA GeForce RTX 3080 Ti

Ghostty 1.0.0-main+4b4d4062 (built from AUR ghostty-git)

Version
  - version: 1.0.0-main+4b4d4062
  - channel: tip
Build Config
  - Zig version: 0.13.0
  - build mode : builtin.OptimizeMode.ReleaseFast
  - app runtime: apprt.Runtime.gtk
  - font engine: font.main.Backend.fontconfig_freetype
  - renderer   : renderer.OpenGL
  - libxev     : main.Backend.io_uring
  - GTK version:
    build      : 4.16.7
    runtime    : 4.16.7
  - libadwaita : enabled
    build      : 1.6.2
    runtime    : 1.6.2

out.mp4

[mitchellh]

Converting to Q&A because I recall some users in the beta hitting this and it's a desktop config issue. We don't render or configure the cursor in any way.

[HE7086]

Looks like a gtk issue:
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/7760
https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/6212
https://blogs.kde.org/2024/10/09/cursor-size-problems-in-wayland-explained/

should be fixed in next gtk release (?)

[pbek]

I have the same issue on KDE Plasma 6 under Wayland. So far I haven't seen that issue with other applications, does anyone know a workaround?

Ghostty 1.0.0

Version
  - version: 1.0.0
  - channel: stable
Build Config
  - Zig version: 0.13.0
  - build mode : builtin.OptimizeMode.ReleaseFast
  - app runtime: apprt.Runtime.gtk
  - font engine: font.main.Backend.fontconfig_freetype
  - renderer   : renderer.OpenGL
  - libxev     : main.Backend.io_uring
  - GTK version:
    build      : 4.16.3
    runtime    : 4.16.3
  - libadwaita : enabled
    build      : 1.6.2
    runtime    : 1.6.2

[HE7086]

Atm you could compile ghostty against other gtk version to workaround that. Any version other than 4.16 should work (read the kde blog mentioned above). But then your other gtk apps might stop working.

[pbek]

Wouldn't the runtime still have the issue? 🤔

[HE7086]

Yeah I meant downgrading the system gtk runtime (or install directly from git source), which might cause issues with other apps.

[topazus]

I also encountered the same cursor issue with gtk 4.17.1.

❯ ghostty --version
Ghostty 1.0.0-dev+0000000

Version
  - version: 1.0.0-dev+0000000
  - channel: tip
Build Config
  - Zig version: 0.13.0
  - build mode : builtin.OptimizeMode.ReleaseFast
  - app runtime: apprt.Runtime.gtk
  - font engine: font.main.Backend.fontconfig_freetype
  - renderer   : renderer.OpenGL
  - libxev     : main.Backend.io_uring
  - GTK version:
    build      : 4.17.1
    runtime    : 4.17.1
  - libadwaita : enabled
    build      : 1.6.2
    runtime    : 1.6.2

[tg90nor]

Interesting. I assumed https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/7760 would fix this, and that is included in 4.17.0 and above.

[tg90nor]

Do you use the breeze cursor theme?

[xulongwu4]

Setting the XCURSOR_THEME env variable to my cursor theme fixed it for me.

[pbek]

Hm, didn't help for me. Neither did XCURSOR_SIZE... What did you set?

[xulongwu4]

I guess it depends on what cursor theme you use now. I set it to Nordic-cursors. Then a reboot fixed it.

[xulongwu4]

My issue was more about the cursor style than the cursor size, so your problem might be different.

[tg90nor]

That's not what this issue is about. It's specifically about the cursor size scaling with the breeze cursor theme (and other themes with bigger image size than nominal size)

[tg90nor]

I'm glad you got your issue fixed though 🙂

[ex1tium]

Launching on Endeavour OS KDE Plasma 6 (Wayland) with GDK_SCALE=1 seems to fix this:

GDK_SCALE=1 ghostty

or not... if the display is in portrait mode the issue comes back, seems to work on landscape mode displays. I have two portrait and two landscape monitors. Scaling set to 100% on each in Display Configuration.

[pbek]

Hm, also doesn't help on NixOS with Plasma 6 (Wayland). 🤔

[nduartech]

With nwg-look switching my cursor theme to Qogir worked

[iynaix]

Fixed for me (Hyprland on NixOS):

(pkgs.ghostty.override {
    wrapGAppsHook4 = pkgs.wrapGAppsNoGuiHook.override {
      isGraphical = true;
      gtk3 =
        (pkgs.__splicedPackages.gtk4.override {
          wayland-protocols = pkgs.wayland-protocols.overrideAttrs (o: rec {
            version = "1.41";
            src = pkgs.fetchurl {
              url = "https://gitlab.freedesktop.org/wayland/${o.pname}/-/releases/${version}/downloads/${o.pname}-${version}.tar.xz";
              hash = "sha256-J4a2sbeZZeMT8sKJwSB1ue1wDUGESBDFGv2hDuMpV2s=";
            };
          });
        }).overrideAttrs
          (o: rec {
            version = "4.17.6";
            src = pkgs.fetchurl {
              url = "mirror://gnome/sources/gtk/${lib.versions.majorMinor version}/gtk-${version}.tar.xz";
              hash = "sha256-366boSY/hK+oOklNsu0UxzksZ4QLZzC/om63n94eE6E=";
            };
            postFixup = ''
              demos=(gtk4-demo gtk4-demo-application gtk4-widget-factory)

              for program in ''${demos[@]}; do
                wrapProgram $dev/bin/$program \
                  --prefix XDG_DATA_DIRS : "$GSETTINGS_SCHEMAS_PATH:$out/share/gsettings-schemas/${o.pname}-${version}"
              done

              # Cannot be in postInstall, otherwise _multioutDocs hook in preFixup will move right back.
              moveToOutput "share/doc" "$devdoc"
            '';
          });
    };
  })