How to reproduce:

1. Open Unity with -force-glcore
2. Open a new project
3. Go to Player settings
4. Set the Mac graphics API to manual
5. Arrange the OpenGLCore API to the top and apply the setting
- At this point, gizmos in the scene view should turn into black rectangles and it becomes impossible to select them by clicking
- If not, then Unity may stop rendering most of its own windows and nothing can be selected anymore
- There are also OPENGL errors that say that the Framebuffer is not complete
- If the second situation arises, Unity can be restarted to get the first situation instead