setComponentZOrderTest_11 is an automated test which changes the z-order of the component at run time. When i execute the testcase, it throws the following exception

[button1,81,35,59x23,label=Button 2]
        at java.awt.EventQueue.invokeAndWait(EventQueue.java:997)
        at setComponentZOrderTest_11.changeComponentZOrder(setComponentZOrderTes
t_11.java:219)
        at setComponentZOrderTest_11.doTest(setComponentZOrderTest_11.java:141)
        at setComponentZOrderTest_11.main(setComponentZOrderTest_11.java:281)
Caused by: java.lang.ArrayIndexOutOfBoundsException: No such child: -1
        at java.awt.Container.getComponent(Container.java:289)
        at java.awt.Component.mixOnZOrderChanging(Component.java:9746)
        at java.awt.Container.setComponentZOrder(Container.java:702)
        at setComponentZOrderTest_11$4.run(setComponentZOrderTest_11.java:221)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
ad.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)

        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)

        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
FocusLost: java.awt.FocusEvent[FOCUS_LOST,temporary,opposite=null,cause=ACTIVATI
ON] on java.awt.Button[button1,81,35,59x23,label=Button 2]


I tested the same testcase in 6u10b31 , its works fine. but in 6u10b33 , the testcase hands & i need to kill the java process. Where as in 6u12 pit b01 build, the testcase throws the exception.  I tested the same in jdk7 b38 & it works fine.  Hence its a regrssion from 6u10 to 6u12.  

Step to reproduce :-
-------------------
1) Run the attached automated testcase
java -DresultsDir=. setComponentZOrderTest_11
If you see the exception then the bug is reproduced.

The exception can be seen on all the platform. ( Solaris 10 , linux & windows xp)