The Mac is still only 9.93% of the computer market world wide. Not a very large community to target even if every Mac owner bought Xara Xtreme.

Not enough return on the time and money investment to create a native Mac version.

Linux is only 0.83% of the world wide computer market.

The figures were taken from TUAW an unofficial Apple weblog http://www.tuaw.com/2009/02/02/apple...windows-drops/