QX11EmbedWidget intermittently fails to lay out correctly

QX11EmbedWidget intermittently fails to lay out correctly. The expected behavior is that one process creates a QX11EmbedContainer and passes its window ID to another process, which creates a QX11EmbedWidget and calls embedInto() with the window ID. What should then happen is that the QX11EmbedWidget becomes parented under the QX11EmbedContainer and gets laid out (e.g., resized) accordingly. What happens in practice is that some times, the QX11EmbedWidget keeps its default size and does not get resized appropriately. Timing seems to matter, as running a test case in the debugger and single stepping through the relevant code makes the problem go away. A good way to see the problem occur (outside the debugger) is to use a shell script loop to run the executable in the background multiple times (e.g., 20 times); although some of these executables will not show the problem, some will.