Okay, looks like you'd need the latest JRE... which isn't available for Mac yet. Can you check which version of Java you have? You can do that by typing "java -version" in a text console. OS 10 has a text console, right? Anyway, I guess I should use AWT instead of Swing for the GUI, and switch back to Java v1.4.2. Then this would definitely work on OS X, but I'm still not sure about the earlier OSes. Fortunately I don't have to change too many lines of code so I'll first try v1.4.2. I'll be back soon with another version. In the meantime it would be great if someone with OS X could test this.