GUI hangs when focus is moved by arrow key in jdk5u32

A JavaSE licensee reproted hang-up problem.

CONFIGURATION:
OS : RHEL6.1
JDK : JDK5u32-b02

REPRODUCE:
1. Compile the attached java program.
$ javac SimpleMenuFrame.java

2. Execute the problem.
$ java SimpleMenuFrame

You will see a window which has 2 puldown menu.

3. Select either of menu0 or memu1 (Keep the pull down menu selected)
4. Move focus by pressing cursor key( "<-" or "->" arrow key)

The following stack trace shows up.
----------------------------
"AWT-EventQueue-0" prio=1 tid=0x8fafe698 nid=0x1b8b runnable [0x8f7d6000..0x8f7d7030]
at sun.awt.X11.XMenuPeer.getDownSelected(XMenuPeer.java:709)
at sun.awt.X11.XMenuBarPeer.selectMenuByKeyPress(XMenuBarPeer.java:231)
at sun.awt.X11.XMenuBarPeer.handleKeyPressOnEDT(XMenuBarPeer.java:551)
at sun.awt.X11.XMenuBarPeer$1.run(XMenuBarPeer.java:515)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:499)
at java.awt.EventQueue.access$000(EventQueue.java:80)
at java.awt.EventQueue$1.run(EventQueue.java:462)
at java.awt.EventQueue$1.run(EventQueue.java:461)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:84)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:471)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)


According to the licensss's investigation, this hang seem to occur between line#706 and line#709.
----------------------------
<j2se/src/solaris/classes/sun/awt/X11/XMenuPeer.java of JDK5u32>
   698 int getDownSelected() {
   699 XMenuItemPeer[] localItems = copyItems();
   700 int nitems = localItems.length;
   701 if (nitems == 0) {
   702 return -1;
   703 }
   704 XMenuItemPeer mi;
   705 int sel = getSelected();
   706 do {
   707 sel = (sel+1) % nitems;
   708 mi = localItems[sel];
   709 } while ((!mi.isEnabled()) || (mi.getLabel() != null && mi.getLabel().equals("-")));
   710 return sel;
   711 }