I have a Swing Window with a JMenuBar used as the system window.
Inside the Swing Window resides a JFXPanel with an Accordion containing some Label components with a tooltip.

When the tooltip appears the Swing Menu disappear and only the Application name is visible. After disappearance ot the tooltip the menu does not recover to the previous state.

It raises instead the following Exception


2013-03-27 12:13:31.880 java[58118:707] *** Assertion failure in -[NSMenuItem setSubmenu:], /SourceCache/AppKit/AppKit-1187.34/Menus.subproj/NSMenuItem.m:757
2013-03-27 12:13:31.881 java[58118:707] Menu to be set as submenu is already a submenu of some menu.
2013-03-27 12:13:31.883 java[58118:707] (
0 CoreFoundation 0x00007fff939f70a6 __exceptionPreprocess + 198
1 libobjc.A.dylib 0x00007fff8f2703f0 objc_exception_throw + 43
2 CoreFoundation 0x00007fff939f6ee8 +[NSException raise:format:arguments:] + 104
3 Foundation 0x00007fff8dcdf6a2 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 189
4 AppKit 0x00007fff8f68ca50 -[NSMenuItem setSubmenu:] + 200
5 liblwawt.dylib 0x000000013cd37862 -[CMenuBar nativeAddMenuAtIndex_OnAppKitThread:] + 312
6 liblwawt.dylib 0x000000013cd37f88 +[CMenuBar activate:modallyDisabled:] + 981
7 liblwawt.dylib 0x000000013cd29975 -[AWTWindow windowDidBecomeKey:] + 141
8 CoreFoundation 0x00007fff939a947a _CFXNotificationPost + 2554
9 Foundation 0x00007fff8dd1b846 -[NSNotificationCenter postNotificationName:object:userInfo:] + 64
10 AppKit 0x00007fff8f79fb46 -[NSWindow becomeKeyWindow] + 1344
11 AppKit 0x00007fff8fcb51cd _NXShowKeyAndMain + 127
12 AppKit 0x00007fff8f7cb06f -[NSWindow sendEvent:] + 5414
13 liblwawt.dylib 0x000000013cd27df0 -[AWTWindow_Normal sendEvent:] + 86
14 AppKit 0x00007fff8f7c7744 -[NSApplication sendEvent:] + 5761
15 libosxapp.dylib 0x000000013cdbfad1 -[NSApplicationAWT sendEvent:] + 179
16 AppKit 0x00007fff8f6dd2fa -[NSApplication run] + 636
17 libosxapp.dylib 0x000000013cdbf9b9 +[NSApplicationAWT runAWTLoopWithApp:] + 156
18 liblwawt.dylib 0x000000013cd1981a -[AWTStarter starter:] + 1591
19 Foundation 0x00007fff8dd65677 __NSThreadPerformPerform + 225
20 CoreFoundation 0x00007fff93976101 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
21 CoreFoundation 0x00007fff93975a25 __CFRunLoopDoSources0 + 245
22 CoreFoundation 0x00007fff93998dc5 __CFRunLoopRun + 789
23 CoreFoundation 0x00007fff939986b2 CFRunLoopRunSpecific + 290
24 java 0x000000010fd1542d CreateExecutionEnvironment + 871
25 java 0x000000010fd0fbdc JLI_Launch + 1952
26 java 0x000000010fd1578a main + 101
27 java 0x000000010fd0f434 start + 52
28 ??? 0x000000000000000e 0x0 + 14
)