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

36.4.0

What operating system(s) are you using?

Windows

Operating System Version

Windows 11 24H2

What arch are you using?

x64

Last Known Working Electron version

Unknown

Expected Behavior

Restore button should replace maximise button after clicking on latter button. And clicking the restore button in maximised mode should restore the window.

Actual Behavior

The maximise button doesn't change to restore button when clicked and the window maximises. Clicking the stuck maximise button (or restore button when maximised using other methods) doesn't restore the window. Dragging the title bar to restore the window just keeps it the same side (with the issue of rounded corners as per #46753.

Testcase Gist URL

https://gist.github.com/aefdd05711802dddfc4d79d7729dbc33

Additional Information

Removing backgroundMaterial from the options results in the button working correctly, but that then removes the backgroundMaterial.