In the Matrex Sourceforge pages Kusashi Nameta (JPN) reports the bug that the Mac OSX version of Matrex does not start correctly.
The problem is that I can test the system only on Windows and Linux, so things like that can happen. There should be someone testing the Mac version before it is published.
The solution, as you can see in my comments, is to add the -XstartOnFirstThread option to the java command.
To do that, edit the matrex_macosx.sh file in the Matrex directory and to:
This should make it work correctly.
I'll publish myself a patched version of the Mac OSX setup file this weekend.