IzPack currently targets Java 1.4. It is becoming aging, yet still widely used in practice. In turn, Java 5 brings a lot of language and API improvements.
One problem that we have is that we cannot really make sure that IzPack is full 1.4-compatible as many of its developers work on Java 5 / Java 6 JDKs. Hence, there is a strong chance that we have occasionaly used method / classes that were not part of prior Java versions. This is very difficult to test and enforce.
The solution to this is to drop 1.4 compatibility in favour of Java 5, then use a backporting tool (e.g., http://retroweaver.sourceforge.net/
or http://retrotranslator.sourceforge.net/
) for those that require Java 1.4 compatibility. This will allow us to use the new language and API enhancements brought by Java 5 while staying backwards compatible.
The following are still open questions: