How to disable menuitems on WindowClose

Hi all!

I have an MDI application (generated by the MDI application wizard in
BCB5.0) which comes with some default File, Edit and Window menu items.
Default the File|Close menuitme is grayed out (disabled) when no MDI
child is opened (automatically done by the TWindowClose class). Even so
are the Cascade/Tile standard window functions. However the Edit menu
doesn't seem to be deactivated when no MDIChild is available. So I have
to do that by myself.

How can I automatically disable other menu items if no MDI child exists?

Do I have to add some code to the TWindowClose base class? Or are there
some simple methods?

Any help appreciated...