@tuomas_h @johnwells Actually, not all windows in the first version of Mac OS X (10.0 Cheetah) had the same title bar size. There was a clear distinction between standard document windows and utility/tool windows. Standard windows had a taller title bar (especially when the toolbar was enabled), while utility windows (like palettes or inspectors) had a much shorter title bar. This is visible in historical screenshots and documented in Apple’s UI guidelines from that era.