Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug report that matches the one I want to file, without success.

Electron Version

30.0.0-beta.7

What operating system are you using?

Windows

Operating System Version

Windows 11

What arch are you using?

x64

Last Known Working Electron version

No response

Expected Behavior

A window with these properties:

frame: false,
backgroundMaterial: "mica",
// Setting WCO is optional but is the simplest way to access maximize and restore controls
titleBarStyle: "hidden",
titleBarOverlay: true

should be able to be maximized and restored/unmaximized with no detrimental effects.

Actual Behavior

When you maximize a frameless window with background material (whether through WCO titlebar controls or programmatically) it causes the following irreversible damage to the window:

• The background material disappears and cannot be re-applied
• The background colour goes pitch black and cannot be changed
• The window's rounded frame, border, shadows, and resize handles are gone when the window is restored

Restoring/unmaximizing the window does not bring back the original styles.

Testcase Gist URL

https://gist.github.com/mitchchn/f38fcd4fdb20e4453c90638ecd5face2

Additional Information

Frameless Mica windows use custom styles to achieve a "thin frame" appearance and I suspect these are being lost/mangled when the window is maximized, and are not being reset when the window is restored.

CC-ing @brhenrique who worked on some improvements to Mica windows without frames and may have some insight here.