Vanishing system buttons

I think I've found a bug in the MDI system somewhere. The system icons
(minimize/maximize/close) on the right of child windows vanish if you
have a main menu on the child window. To demonstrate:

1. Create new MDI project from FileNew/Project/MDIApp
2. Add a main menu to the child class with one menu, one item (must have
one item or GPF)
3. Set MDIChild WindowState to wsMaximized (not necessary but quicker)
4. Run
5. Click New button to get first child window
6. Click New button again for second child window
7. Close second child by clicking on x at the far right.
System buttons have vanished from first child window.

Even tiling does not restore the buttons but they do return after a bit
of ceremony
- tile
- double click child caption bar to maximise (buttons have returned but
'x' is grey)
- click 'restore' (middle) button - buttons have returned fully.

Without wsMaximized the windows appear ok but if you open two child
windows, maximise one, close is with 'x', the problem is again evident.

Without the menu on the child form everything works fine.

Roland Seidel