Background opacity not working with Fedora Linux 41

[bengentil]

Issue

Setting background-opacity to a value < 1 doesn't make the background transparent, only brighter (even with value like 0.10)

Here a screenshot with on top ghostty with background-opacity = 0.94 and below alacritty with a similar config showing the same tmux window.

Environment

• Fedora 41
• sway 1.10
• wayland 1.23.0-2
• Ghostty 0.1.0-main+a34c8ba7

logs

info: ghostty version=0.1.0-main+a34c8ba7
info: ghostty build optimize=ReleaseFast
info: runtime=apprt.Runtime.gtk
info: font_backend=font.main.Backend.fontconfig_freetype
info: dependency harfbuzz=8.4.0
info: dependency fontconfig=21402
info: renderer=renderer.OpenGL
info: libxev backend=main.Backend.io_uring
info(os): setlocale from env result=en_US.utf8
info(gtk): GTK version build=4.16.5 runtime=4.16.5
info: reading configuration file path=/home/benjamin/.config/ghostty/config
info(config): config has 'keybind = clear', all keybinds cleared
info(config): config has 'keybind = clear', all keybinds cleared
info(config): default shell source=env value=/usr/bin/fish
info(gtk): libadwaita version build=1.6.2 runtime=1.6.2

(process:20131): Adwaita-WARNING **: 23:29:54.920: Using GtkSettings:gtk-application-prefer-dark-theme with libadwaita is unsupported. Please use AdwStyleManager:color-scheme instead.
EGL API version 1.5 found
 - Vendor: Mesa Project
 - Version: 1.5
 - Device: /dev/dri/renderD128, 226 128
 - Client APIs: OpenGL OpenGL_ES
 - Extensions:
        EGL_ANDROID_blob_cache
        EGL_ANDROID_native_fence_sync
        EGL_EXT_buffer_age
        EGL_EXT_config_select_group
        EGL_EXT_create_context_robustness
        EGL_EXT_image_dma_buf_import
        EGL_EXT_image_dma_buf_import_modifiers
        EGL_EXT_pixel_format_float
        EGL_EXT_present_opaque
        EGL_EXT_protected_content
        EGL_EXT_query_reset_notification_strategy
        EGL_EXT_surface_compression
        EGL_EXT_swap_buffers_with_damage
        EGL_IMG_context_priority
        EGL_KHR_cl_event2
        EGL_KHR_config_attribs
        EGL_KHR_context_flush_control
        EGL_KHR_create_context
        EGL_KHR_create_context_no_error
        EGL_KHR_fence_sync
        EGL_KHR_get_all_proc_addresses
        EGL_KHR_gl_colorspace
        EGL_KHR_gl_renderbuffer_image
        EGL_KHR_gl_texture_2D_image
        EGL_KHR_gl_texture_3D_image
        EGL_KHR_gl_texture_cubemap_image
        EGL_KHR_image_base
        EGL_KHR_no_config_context
        EGL_KHR_reusable_sync
        EGL_KHR_surfaceless_context
        EGL_KHR_swap_buffers_with_damage
        EGL_KHR_wait_sync
        EGL_MESA_configless_context
        EGL_MESA_drm_image
        EGL_MESA_gl_interop
        EGL_MESA_image_dma_buf_export
        EGL_MESA_query_driver
        EGL_MESA_x11_native_visual_id
        EGL_WL_bind_wayland_display
        EGL_WL_create_wayland_buffer_from_image
 - Selected fbconfig: R8G8B8A8, depth 0, stencil 0
          high depth: R16G16B16A16 float, depth 0, stencil 0
Creating EGL context version 3.2 (debug:no, forward:no, legacy:no, es:no)
Using OpenGL backend EGL
Creating EGL context version 3.2 (debug:no, forward:no, legacy:no, es:no)
OpenGL version: 4.6 (core)
GLSL version: 4.60
Max texture size: 16384
Enabled features (use GDK_GL_DISABLE env var to disable):
    debug: ✓
    unpack-subimage: ✓
    half-float: ✓
    sync: ✓
    base-instance: ✓
    buffer-storage: ✓
OpenGL version: 4.6 (core)
GLSL version: 4.60
Max texture size: 16384
Enabled features (use GDK_GL_DISABLE env var to disable):
    debug: ✓
    unpack-subimage: ✓
    half-float: ✓
    sync: ✓
    base-instance: ✓
    buffer-storage: ✓
Creating EGL context version 3.3 (debug:no, forward:no, legacy:no, es:no)
OpenGL version: 4.6 (core)
GLSL version: 4.60
Max texture size: 16384
Enabled features (use GDK_GL_DISABLE env var to disable):
    debug: ✓
    unpack-subimage: ✓
    half-float: ✓
    sync: ✓
    base-instance: ✓
    buffer-storage: ✓
info(grid): loaded OpenGL 4.6
info(font_shared_grid_set): font regular: Fira Mono
info(font_shared_grid_set): font bold: Fira Code Bold Nerd Font Complete Mono
info(font_shared_grid_set): font italic: Fira Code Regular Nerd Font Complete Mono
info(font_shared_grid_set): font bold_italic: Fira Code Bold Nerd Font Complete Mono
info(io_exec): found Ghostty resources dir: /home/benjamin/.local/share/ghostty
info(io_exec): shell integration automatically injected shell=termio.shell_integration.Shell.fish
warning(gtk): unimplemented action=apprt.action.Action.Key.cell_size
warning(gtk): unimplemented action=apprt.action.Action.Key.size_limit
info(io_exec): started subcommand path=/bin/sh pid=20157
info(io_exec): subcommand cgroup=-
Creating EGL context version 3.2 (debug:no, forward:no, legacy:no, es:no)
OpenGL version: 4.6 (core)
GLSL version: 4.60
Max texture size: 16384
Enabled features (use GDK_GL_DISABLE env var to disable):
    debug: ✓
    unpack-subimage: ✓
    half-float: ✓
    sync: ✓
    base-instance: ✓
    buffer-storage: ✓
Using fractional scale 1 for EGL window (1000 600 => 1000 600)
Using fractional scale 1 for EGL window (1186 595 => 1186 595)
warning(stream): unimplemented OSC callback: terminal.osc.Command{ .end_of_command = terminal.osc.Command.Command__struct_95700{ .exit_code = null } }
warning(stream): unimplemented OSC command: end_of_command
info(grid): reallocating GPU buffer old=0 new=8
info(grid): reallocating GPU buffer old=8 new=38

[mitchellh]

Converted to a discussion until we get confirmation this is a bug in Ghostty. All Ghostty does for transparency is set GTK values, so this to me is screaming like an upstream issue. But happy to be proven wrong if we can fix it. :)

[bengentil]

Doing a full build (by removing .zig-cache) fixed the issue. I probably had in the cache an object compiled with an older GTK version.

Sorry for the noise