GTK/Wayland: split resize shows a one-frame stale-geometry "snap back" (1.3.1, AMD GPU)

[lascrountch]

Issue Description

During a split resize, the resized pane is redrawn for a single frame at its previous geometry before snapping to the new size (a visible one-frame "snap back"). Happens with a "resize_split" keybind.

info(opengl): loaded OpenGL 4.6 is logged on every resize.

Related to #8208 (whole-window flicker on split changes, fixed in 1.3.0). On 1.3.1 a distinct, smaller artifact remains. Possibly the same phenomenon as #8773 and #9376.

Renderer:

• GPU: AMD Radeon Graphics (radeonsi, gfx1151) - Ryzen AI Max+ 395 "Strix Halo"
• OpenGL: 4.6 (Compat) Mesa 25.2.8
• Wayland session, GNOME Shell 46

issue_ghostty.mp4

Expected Behavior

Resizing a split should look smooth, with no flicker.

Actual Behavior

During the resize, the pane flickers: for one frame it is drawn at its previous geometry before snapping to the new size.

Reproduction Steps

1. Start Ghostty (reproduces with an empty configuration).
2. Open a bottom split: ctrl+shift+e (new_split:down).
3. Resize the split, drag the horizontal divider with the mouse, or use a resize_split keybind.
4. Watch the resized pane during the resize: for one frame it is drawn at its previous geometry before snapping to the new size.

Ghostty Logs

info: ghostty version=1.3.1
info: ghostty build optimize=ReleaseFast
info: runtime=.gtk
info: font_backend=.fontconfig_freetype
info: dependency harfbuzz=8.3.0
info: dependency fontconfig=21500
info: renderer=renderer.generic.Renderer(renderer.OpenGL)
info: libxev default backend=io_uring
info(os_locale): setlocale from env result=en_US.UTF-8
info(gtk): GTK version build=4.14.5 runtime=4.14.5
info(gtk): libadwaita version build=1.5.0 runtime=1.5.0
info: reading configuration file path=/home/tristan/.config/ghostty/config
warning: error reading optional config file, not loading err=error.FileIsEmpty path=/home/tristan/.config/ghostty/config.ghostty
warning(config): both config files `/home/tristan/.config/ghostty/config` and `/home/tristan/.config/ghostty/config.ghostty` exist.
warning(config): loading them both in that order
info(config): default shell source=env value=/usr/bin/zsh
warning(gtk_ghostty_application): setting GDK_DEBUG=gl-disable-gles,gl-no-fractional,vulkan-disable
warning(gtk_ghostty_application): setting GDK_DISABLE=color-mgmt
warning(glib): WARNING: Gtk: Theme parser error: style.css:140:17-19: Unexpected data at end of hsl() argument
info(opengl): loaded OpenGL 4.6
info(font_shared_grid_set): font regular: DejaVu Sans Mono
info(font_shared_grid_set): font bold: DejaVu Sans Mono Bold
info(font_shared_grid_set): font italic: DejaVu Sans Mono Oblique
info(font_shared_grid_set): font bold_italic: DejaVu Sans Mono Bold Oblique
info(io_exec): found Ghostty resources dir: /usr/share/ghostty
info(io_exec): shell integration automatically injected shell=.zsh
warning(gtk_ghostty_application): unimplemented action=.cell_size
info(io_exec): started subcommand path=/bin/sh pid=33995
info(stream): OSC 1 (change icon) received and ignored icon=~
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(io_exec): found Ghostty resources dir: /usr/share/ghostty
info(io_exec): shell integration automatically injected shell=.zsh
warning(gtk_ghostty_application): unimplemented action=.cell_size
info(io_exec): started subcommand path=/bin/sh pid=34309
info(stream): OSC 1 (change icon) received and ignored icon=~
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6
info(opengl): loaded OpenGL 4.6

Ghostty Version

Ghostty 1.3.1

Version
  - version: 1.3.1
  - channel: stable
Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .gtk
  - font engine   : .fontconfig_freetype
  - renderer      : renderer.generic.Renderer(renderer.OpenGL)
  - libxev        : io_uring
  - kernel version: 6.17.0-1028-oem
  - desktop env   : other
  - GTK version   :
    build         : 4.14.5
    runtime       : 4.14.5
  - libadwaita    : enabled
    build         : 1.5.0
    runtime       : 1.5.0
  - libX11        : enabled
  - libwayland    : enabled

OS Version Information

Ubuntu 24.04.4 LTS

(Linux only) Display Server

Wayland

(Linux only) Desktop Environment/Window Manager

GNOME Shell 46.0

Minimal Ghostty Configuration

Reproduces with an empty configuration

Additional Relevant Configuration

No response

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.

[ngocphamm]

I think I see the same issue, plus, I just noticed that if I use keyboard shortcuts to resize split panes, Ghostty leaks a lot of memory very very quickly (now at 3.6G, after holding the shortcut keys for ~5s). Resizing using mouse is fine.

Ubuntu 26.04 + Gnome Wayland

~ »  ghostty +version
Ghostty 1.3.1

Version
  - version: 1.3.1
  - channel: stable
Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .gtk
  - font engine   : .fontconfig_freetype
  - renderer      : renderer.generic.Renderer(renderer.OpenGL)
  - libxev        : io_uring
  - kernel version: 7.0.0-27-generic
  - desktop env   : other
  - GTK version   :
    build         : 4.22.1
    runtime       : 4.22.4
  - libadwaita    : enabled
    build         : 1.9.0
    runtime       : 1.9.0
  - libX11        : enabled
  - libwayland    : enabled