SecurityException when running webstart apps if console is not shown

If I run a webstart app with no console, using the latest build of the deploy forest, the app fails to run, and I see the following exception in the log file:

java.lang.ExceptionInInitializerError
at com.sun.glass.ui.Window.<init>(Unknown Source)
at com.sun.glass.ui.win.WinWindow.<init>(Unknown Source)
at com.sun.glass.ui.win.WinApplication.createWindow(Unknown Source)
at com.sun.javafx.tk.quantum.WindowStage.initPlatformWindow(Unknown Source)
at com.sun.javafx.tk.quantum.WindowStage.init(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.createTKStage(Unknown Source)
at javafx.stage.Stage.impl_visibleChanging(Unknown Source)
at javafx.stage.Window$13.invalidated(Unknown Source)
at javafx.beans.property.BooleanPropertyBase.markInvalid(Unknown Source)
at javafx.beans.property.BooleanPropertyBase.set(Unknown Source)
at javafx.stage.Window.setVisible(Unknown Source)
at javafx.stage.Stage.setVisible(Unknown Source)
at com.javafx.experiments.digitalclock.Main.start(Main.java:63)
at com.sun.javafx.applet.FXApplet2$1.run(Unknown Source)
at com.sun.javafx.application.PlatformImpl$3.run(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(Unknown Source)
at com.sun.glass.ui.win.WinApplication$1$1.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at sun.plugin2.applet.SecurityManagerHelper.checkAccessHelper(Unknown Source)
at sun.plugin2.applet.FXAppletSecurityManager.checkAccess(Unknown Source)
at java.lang.ThreadGroup.checkAccess(Unknown Source)
at java.lang.Thread.init(Unknown Source)
at java.lang.Thread.<init>(Unknown Source)
at com.sun.glass.utils.Disposer.<clinit>(Unknown Source)
... 19 more

If I enable the Java Console then the app runs fine. The full log file is attached.