When the event queue is full, win32 hangs in several places. Such as in
src/win32/sun/windows/awt_Component/cpp:

    HANDLE hevt = CreateEvent(NULL, TRUE, FALSE, NULL);
    ASSERT(hevt);
    ::PostMessage(p->GetHWnd(), WM_AWT_QUEUE_SYNC, (WPARAM)hevt, 0);
    WaitForSingleObject(hevt, INFINITE);

If the event queue is full the PostMessage will fail and WaitForSingleObject
will wait forever. One should verify the PostMessage and either retry or fail
more gracefully if it fails.