Flat Button is a Carbon implentation of push button and pop-up menu controls found only in Mac OS X 10.3 and then only in Cocoa apps. Flat Button is an HIView-based control and is thus compatible with all Carbon apps on Mac OS X 10.2 and newer.
What's new in Flat Button Carbon
Flat Button Carbon is now a Universal binary compatible with PowerPC 10.3.9 and PPC/Intel 10.4.x
Internal code cleanup for improved operation and OS support