That is because the green button is a «zoom» button, which maximizes the window to display its contained document: https://blog.xoria.org/macos-tips/#window-man

That is because the green button is a «zoom» button, which maximizes the window to display its contained document: https://blog.xoria.org/macos-tips/#window-management https://blog.xoria.org/macos-tips/#window-management I am not sure if I agree with the choice either, but that’s the explanation.