JEP253 aims to prepare JavaFX for Project Jigsaw by defining public APIs for functionality that will become inaccessible due to modularization.
Keeping references around to remove listeners is a hazard. ListenerHandles encapsulate the complexity and LibFX has an implementation.
Release post for LibFX 0.2.0 including and pointers to GitHub, Feature descriptions, Maven coordinates and the Javadoc.
A quick step by step guide how to use the JavaFX sources in Eclipse by attaching them to the current JDK.