JavaFX state is not properly cleaned after destroying all JavaFX components. 
It will result on an exception if you create a new JavaFX component.

Steps to reproduce:

1 - Create a SWT application and add a FXCanvas
2 - Dispose the FXCanvas. The application will no longer have JavaFX components.
3 - Create a new FXCanvas.
4 - The application will throw "java.lang.IllegalStateException: Not on FX application thread"


Problems:

When the last JavaFX component is destroyed, the JavaFX shutsdown and cleans the state, but not properly. 
The static fields "initialized" at "com.sun.javafx.application.PlatformImpl" and "application" at "com.sun.glass.ui.Application" stays dirty.