macOS: hidden-titlebar window starts opaque

[xicodomingues]

Issue Description

On macOS, a new Ghostty instance sometimes ignores background-opacity and starts with a fully opaque terminal background when using:

background-opacity = 0.7
macos-titlebar-style = hidden

The configured opacity becomes visible immediately after either:

• Reloading the unchanged configuration with Cmd+Shift+Comma.
• Creating a split with Cmd+D.

Changing application or window focus does not fix it.

I tested the complete rendered configuration using automated immediate screenshots. The two configurations differed by exactly one line:

-macos-titlebar-style = hidden
+macos-titlebar-style = transparent

On Ghostty 1.3.2-main-+c4c61c5a8:

Configuration	Result
macos-titlebar-style = hidden	10/10 launches initially opaque
macos-titlebar-style = transparent	10/10 launches initially transparent

Possibly related reports:

• macOS: Config reload inconsistent with system theme #8282 reports an incorrect titlebar appearance on new windows that is repaired by reloading the configuration, but concerns system theme synchronization.
• macOS: exiting fullscreen does not restore background-opacity #3553 reports background opacity not being restored after exiting fullscreen with a hidden titlebar.

The fact that both configuration reload and creating a split repair the background suggests that the initial window appearance is not always synchronized after the hidden-titlebar window becomes visible.

Written mostly by AI, revised by me.

Also not referred, might be important: I'm using aerospace in mac, so it may be related, not sure.

Expected Behavior

The terminal background should use the configured background-opacity when the new window first becomes visible, including when macos-titlebar-style = hidden.

Actual Behavior

The new window initially has a fully opaque terminal background. The configured opacity is applied after reloading the configuration or creating a split.

Reproduction Steps

1. Launch a separate Ghostty instance:

/usr/bin/open -na Ghostty --args \
  --config-default-files=false \
  --background-opacity=0.7 \
  --macos-titlebar-style=hidden

1. Observe that the new window's terminal background is fully opaque.
2. Press Cmd+Shift+Comma to reload the unchanged configuration.
3. Observe that the configured transparency is now applied.

Alternatively, after step 2, press Cmd+D to create a split. This also applies the configured transparency.

As a control, replace hidden with transparent in the launch command. The new window starts transparent without requiring either action.

Ghostty Logs

No relevant log messages were observed during reproduction.

Ghostty Version

Ghostty 1.3.2-main-+c4c61c5a8

Version
  - version: 1.3.2-main-+c4c61c5a8
  - channel: tip
Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .none
  - font engine   : .coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

macOS 26.5.2 (25F84)

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

background-opacity = 0.7
macos-titlebar-style = hidden

Additional Relevant Configuration

I'm using aerospace, may be relevant

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.

[bo2themax]

Thanks #13324