When using JSmooth 0.9.7 in headless mode, an exception will be thrown
in line 236 of ExeCompiler.java, because a dummy JLabel instance is
created for a MediaTracker.
I simply commented out lines 236 to 243 inclusive; using the media
tracker is not necessary, at least if the .ico file is supported by the ICO
decoder contained in JSmooth (it blocks until the .ico file is read, anyway).
After making this small change and recompiling, I can now invoke
JSmooth on a headless Linux machine to build the .exe-Wrapper.