Summary

Initializing the JavaFX runtime via Platform.startup and then launching an Application on the JavaFX Application should throw IllegalStateException.

Problem

The current behavior causes a deadlock, instead of a reasonable Exception.

Solution

Application.launch will now throw an IllegalStateException, when it's called from the JavaFX Application Thread.

Specification

In the javafx.application.Application class, add the following to the API docs of these two methods:

void launch(Class<? extends Application> appClass)
void launch(Class<? extends Application> appClass, String... args)

     * @throws IllegalStateException if this method is called from the JavaFX application thread.