This happens in b12 PIT bundle. When errors happen in applet loading. A red x box is shown. Left click the box will pop up a java webstart style dialog showing applicaiton error with "details" and "ignore" buttons. Click "details" does nothing and probably trigger an exception in java console. The exception may be related to CR 6659532.

The following is output from console:

modalityPushed for applet ID 1 with dialog sun.plugin.util.PluginSysUtil$DummyDialog[dialog3,-100,-100,123x34,layout=java.awt.BorderLayout,APPLICATION_MODAL,defaultCloseOperation=HIDE_ON_CLOSE,rootPane=javax.swing.JRootPane[,3,29,117x2,layout=javax.swing.JRootPane$RootLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=16777673,maximumSize=,minimumSize=,preferredSize=],rootPaneCheckingEnabled=true]
Calling synthesizeWindowActivation(true) for applet 1
  Called Dialog.toFront() / requestFocus() for blocker of applet ID 1
Calling synthesizeWindowActivation(false) for applet 1
PluginMain: processing HeartbeatMessage
PluginMain: processing SynthesizeWindowActivationMessage
PluginMain: processing SynthesizeWindowActivationMessage
modalityPopped for applet ID 1
Exception in thread "AWT-EventQueue-1" java.lang.ClassCastException: com.sun.deploy.services.WPlatformService cannot be cast to sun.plugin.services.BrowserService
	at sun.plugin2.main.client.Plugin2ConsoleController.isIconifiedOnClose(Unknown Source)
	at com.sun.deploy.util.ConsoleWindow.showConsole(Unknown Source)
	at sun.plugin.JavaRunTime$2.run(Unknown Source)
	at java.awt.event.InvocationEvent.dispatch(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)
Calling synthesizeWindowActivation(true) for applet 1