That's not part of the new design. You're probably used to seeing a maximized Chrome windows, which don't have that space. The space is present in free-floati

That's not part of the new design. You're probably used to seeing a maximized Chrome windows, which don't have that space. The space is present in free-floating windows to provide space for the mouse to grab and move it around (because grabbing on a tab would split the tab out into a new window). At least, this is how it works in Windows, and (iirc) quite a few *nix window managers. Can't say for sure; I'm currently on i3 with window decorations disabled and my floating windows don't have it (and I can drag using any part of a floating window with alt+drag). Don't know how OSX behaves.