Bug: Persisted fullscreen state can leave the Windows app borderless and impossible to resize

[dorianb04]

Short summary

On Windows, the app can persist "fullscreen": true in %APPDATA%\com.github.githubapp\.window-state.json.

When this happens, the app opens in a borderless fullscreen-like window that cannot be resized or restored through the normal window controls.

Affected version or release

GitHub Copilot desktop 2.98.0 / app runtime 1.1.15 / bundled Copilot CLI 1.0.83-5

Installation context

GitHub Copilot desktop app installed locally on:

• Windows 11 Pro
• Build 26100
• ARM64

What happened?

The fullscreen property somehow became enabled in the persisted window state:

"fullscreen": true

The application then opened as a borderless window without any discoverable way to return to the regular decorated and resizable window mode.

The only workaround I found was:

1. Close the GitHub Copilot app.
2. Open %APPDATA%\com.github.githubapp\.window-state.json.
3. Manually change "fullscreen": true to "fullscreen": false.
4. Restart the application.

After changing that value, the normal window borders and resize controls were restored.

This workaround is not discoverable and requires editing an internal configuration file, so a non-technical user could easily assume that the application is permanently broken.

Steps to reproduce

The action that initially caused the app to persist fullscreen: true is unknown, but the resulting state can be reproduced:

1. Close the GitHub Copilot app.
2. Set "fullscreen": true in %APPDATA%\com.github.githubapp\.window-state.json.
3. Launch the app.
4. Observe that the window opens borderless and cannot be resized or restored using the normal Windows window controls.
5. Change the value back to false and restart the app.
6. Observe that the normal resizable window is restored.

Expected behavior

The application should always provide a discoverable way to exit fullscreen mode, such as a menu command or a standard keyboard shortcut.

A persisted fullscreen state should not leave the user trapped in a borderless, non-resizable window. The app could also validate or safely reset the persisted window state when the corresponding fullscreen mode cannot be exited normally.

Additional context

This is a Windows-specific recovery problem involving the persisted .window-state.json file. It appears distinct from the existing macOS issues about resizing after display or resolution changes.

[gimenete]

This will be fixed in the next release. Please reopen if you still experience the issue.

[github-app-releaser]

This issue was fixed in the public GitHub Copilot app release v1.1.17.