Demo of using the Quartz Debug developer tool on MacOS X 10.4 to change the UI to fractional sizes.

Natively drawn shapes (including subpixel-rendered text, and the round rect step outlines in Automator) scale well as they are drawn at scale. Any kind of bitmap image (including all the "lickable" OS X controls) scale poorly.

1.0 scale (native)

0.75 scale (downscale)

1.58 scale (upscale)