Giving Tahoe titlebars a background really accentuates how chunky they are.
@johnwells @tuomas_h I am not a fan of the Tahoe aesthetics, but you are comparing incomparable: the window in the background is a tool window with a smaller title bar, while the window in the foreground is a standard window. To compare these two UI epochs, compare windows of the same type.
@vancura @johnwells In that era of Mac OS X, that was always the size of the title bar, whether or not there was a toolbar below it.
@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.

@vancura @tuomas_h Tuomas is correct. The background screenshot is of an OS X 10.0 Finder window using a standard titlebar.

Here's a side by side. The utility window screenshot is 10.4, but the height was unchanged from 10.0.

@johnwells @tuomas_h You're right, it was 7px smaller. Sorry!