Pointer-shape probe

A clickable raylib grid that asks GLFW for every standard cursor token (cursor-shapes.d). Hue's GUI splitters and scrollbars go through the same SetMouseCursor path; if a shape cannot be realised the pointer snaps back to the default arrow.

# from a sparkles nix shell
dub run --single --compiler=ldc2 \
  docs/research/window-system-integration/cursor-shapes/cursor-shapes.d

Hover or click a tile. The program calls raylib SetMouseCursor every frame.

Last reviewed: August 14, 2026

What we found (GNOME / Wayland)

Those extra cursor tokens in the GLFW changelog (GLFW_RESIZE_NWSE_CURSOR, GLFW_POINTING_HAND_CURSOR, …) landed in 3.4, not 3.5.1. 3.5.1 did not add compositor-side cursor shapes.

The pipeline hue uses is:

sparkles PointerShape
  → SetMouseCursor (raylib rcore_desktop_glfw.c)
  → glfwCreateStandardCursor(0x00036000 + cursor)
  → Wayland: wl_cursor_theme_get_cursor(XDG name, else X11 name)

Stock GLFW 3.5.1 still does not speak wp_cursor_shape_v1. On Wayland it only uploads XCursor pixmap buffers via wl_pointer.set_cursor. See the GLFW deep-dive.

A probe against this machine's nixpkgs glfw 3.5.1 (/tmp/glfw-cursor-probe.c):

shape	result
ARROW	ok
IBEAM	ok
POINTING_HAND	ok
RESIZE_ALL	ok
CROSSHAIR	NULL ("crosshair" missing)
RESIZE_EW	NULL ("ew-resize" then X11 name missing)
RESIZE_NS	NULL ("ns-resize" then X11 name missing)
RESIZE_NWSE/NESW	NULL (no X11 fallback)
NOT_ALLOWED	NULL (no X11 fallback)

Hue's splitters and scrollbars ask for ewResize / nsResize. Those are exactly the shapes that fail, so glfwSetCursor(window, NULL) snaps back to the default arrow. That is why the pointer appeared stuck after the 3.5.1 upgrade.

/usr/share/icons/Adwaita on this host has no cursors/ directory. Recent Adwaita dropped XCursor files in favour of compositor-owned shapes. GLFW never asked the compositor for a named shape.

Raylib also allocates a new GLFWcursor on every SetMouseCursor call and never caches or destroys it. Hue does this every frame. Harmless when creation succeeds; when it fails, it repeatedly resets the cursor to default.

Fix (applied)

nix/d-toolchain.nix overlays glfw / glfw3 onto PetarKirov/glfw at 1e59848ba2856c25515a80f52e97c78d5412395e: glfw#2679 rewritten on 3.5.1.

After that overlay, glfwCreateStandardCursor succeeds for every standard token on this GNOME/Wayland session (including RESIZE_EW / RESIZE_NS). The D probe emits only the usual Wayland "window position unavailable" warnings, not GLFW_CURSOR_UNAVAILABLE.

Raylib should still cache standard cursors. That is no longer what hides the shapes.