In previous versions of Java, Java FX was either shipped in the /lib folder to be added to a classpath or as a separate download. In Java FX 8, Java FX is added as an extension. See the following screenshot taken from the Eclipse IDE (Luna) for the difference in treatment between rt.jar and jfxrt.jar.
|JavaFX JAR Added as an Extension|
This produces the following warnings in the Java source.
|Eclipse Warning of Use of Extension|
And the fix is to navigate to the build settings to turn off the Forbidden References warning.
|Turn Off Forbidden Reference Warnings|
This particular project is based on Maven, and Maven doesn't produce any such warnings about the use of the extension. So, it's safe to turn off. This wasn't an issue with my Java 6 and Java 7 uses of FX because in those cases, I explicitly added Java FX to the classpath which makes it portable to other Java installations.