MacLux Pro is built on a Classic Macintosh application class library. However, version 2.1 has been made Carbon compatible which means it runs directly under OS-X.
MacLux Pro was designed for the older Mac operating system which is reflected in its interface. MacLux Pro does not take advantage of operating system features that are found in software written specifically for OS-X. Some OS-X specific behaviors particularly those involving windows and the dock may not work as well in MacLux Pro as in applications that are written using Cocoa or a Carbon specific framework. Improvements have been made to make MacLux Pro more compatible with OS-X. These cumulative fixes are included in the latest version, v2.2.
MacLux Pro is compiled to run on a PowerPC processor. It runs on a Macintosh with an Intel processor using Apple's Rosetta emulation technology. Rosetta is included as part of OS-X 10.4, Tiger, and 10.5, Leopard. Rosetta works so transparently that you are not even aware of its existence. MacLux Pro runs just like it was a native Intel application.
OS-X 10.6, Snow Leopard, may not include Rosetta in its standard installation. (Snow Leopard itself will not run on PowerPC based Macs.) In order to run MacLux Pro under 10.6, you may need to install Rosetta or include it as an option when upgrading to Snow Leopard.