HTMLEditor has a major memory leak:

import javafx.application.Application;
import javafx.scene.web.HTMLEditor;
import javafx.stage.Stage;

public class JavaFxTest2 extends Application {
public void printMem() {
Runtime runtime = Runtime.getRuntime();
long usedMemory = runtime.totalMemory() - runtime.freeMemory();
System.out.println(""+usedMemory);
}
public void start(final Stage stage) {
for (int i=0;i<100;i++) {
HTMLEditor h = new HTMLEditor();
if (i%10==0) {
System.gc();
printMem();
}
}
}
public static void main(String[] args) {
Application.launch(args);
}
}

Gives the following output:

2595080
8698824
14885992
20936536
27121272
33307720
39492520
45562200
51748120
57934616