JavaFX technology is very early in its development. The JavaFX Script language, currently being developed with the community's help (see OpenJFX project), will have a grammar and syntax that are open source. Some parts of the language are already open source. The JavaFX compiler, runtime engine, player, and tools currently under development are not expected to be open source. You can participate in the OpenJFX Compiler Project, which focuses on creating a JavaFX compiler to translate JavaFX scripts into JVM class files (bytecode). This compiler will leverage and extend the JDK's javac compiler capabilities.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!