We're seeing this error as well. In our case, it occurs when a child NSWindow contains an editable text field: closing that window and opening a new one triggers the crash. We've found that removing the editable text field prevents the crash, but this is clearly a bug in Golden Gate Beta 3...

@Frameworks Engineer We also encountered an issue with transparent NSWindows on 26.3 RC (FB21879511). On 26.3 RC, mouse events are intercepted by the entire transparent window rather than only the opaque regions. As a result, any third-party app that uses full-screen overlay windows blocks system interactions while the overlay is present on the screen.

I agree, the new UI is horrible... The inline changes are one thing, but there is also no file hierarchy displayed. This means that if you have two files with the same name but in different directories, you can't tell which one has been modified. Please add an option to use the legacy view. 🙏