Window border is visible in non-native fullscreen on MacOS Tahoe

[anorm]

Issue Description

When using config macos-non-native-fullscreen, and entering fullscreen, a grey border is still visible around the screen. This started with MacOS Tahoe.

Expected Behavior

Only the terminal is visible, no border.

Actual Behavior

A border is still visible.

Reproduction Steps

1. Configure the macos-non-native-fullscreen configuration setting
2. Reload config
3. Enter fullscreen

Ghostty Logs

No response

Ghostty Version

Ghostty 1.2.3

Version
  - version: 1.2.3
  - channel: stable
Build Config
  - Zig version   : 0.14.1
  - build mode    : builtin.OptimizeMode.ReleaseFast
  - app runtime   : apprt.Runtime.none
  - font engine   : font.main.Backend.coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

MacOS 26.1 (build 25B78)

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

macos-non-native-fullscreen = true

Additional Relevant Configuration

The issue is visible with this configuration, but since the default background color is grey, it can be a bit hard to see. Use a higher contrast theme to make it easier to see.

theme = CGA

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.

[jonesn3]

Can be seen pretty easily if you set

macos-non-native-fullscreen = true
background = black

[dzhlobo]

macOS 26 renders windows differently and it seems it renders window borders unless we explicitly specify that a window must be borderless: https://ampcode.com/threads/T-019cd797-b49b-77ca-b702-ff18027fc6bf

[dzhlobo]

I tried to apply .borderless but it didn't help. AI suggested to also disable window shadow and after some trial and error I was able to remove this 1px border.

The thing is only shadow matters. If window.hasShadow = true macOS draws tiny 1px border around the whole window. If you magnify and inspect other windows on macOS 26 -- you'll see this border.

So, 2 things.

1. You can disable window shadow and you won't see the border in current version of Ghostty:

macos-non-native-fullscreen = true
macos-window-shadow = false

2. It still would be great to disable shadow in non-native fullscreen. It's logical (we can't look at shadow in fullscreen) and would help to avoid confusions.

[denumerable]

Seems like this has been solved now by the IINA team and mentioned here:

libsdl-org/SDL#15005

[rhodes-b]

#11325
and a ghostty PR doing the same thing