The attached test program fails on Mac when run with a security manager. To reproduce, run the app as follows:

$ java -Djava.security.manager HelloJFXPanelWeb
createScene: calling Platform.runLater
PlatformImpl.runLater returns
Platform.runLater :: run
Exception in thread "JavaFX Application Thread" java.lang.ExceptionInInitializerError
at javafx.scene.web.WebEngine.<init>(WebEngine.java:870)
at javafx.scene.web.WebEngine.<init>(WebEngine.java:845)
at javafx.scene.web.WebView.<init>(WebView.java:269)
at HelloJFXPanelWeb$2.run(HelloJFXPanelWeb.java:66)
at com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295)
at com.sun.javafx.application.PlatformImpl$$Lambda$55/657906486.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294)
at com.sun.javafx.application.PlatformImpl$$Lambda$54/647865547.run(Unknown Source)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "modifyThreadGroup")
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:457)
at java.security.AccessController.checkPermission(AccessController.java:884)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:549)
at java.lang.SecurityManager.checkAccess(SecurityManager.java:729)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.Thread.init(Thread.java:391)
at java.lang.Thread.init(Thread.java:349)
at java.lang.Thread.<init>(Thread.java:548)
at com.sun.webkit.Disposer.<clinit>(Disposer.java:61)
... 10 more