This package creates the main window for Diagnostics. It also contains
the Commands object with all command actions which need to be shared amongst
various pieces, and two special listeners for Save and Edit commands in menus.
The menu listeners are both derived from SlowInstanceMenuListener. This
menu listener, coded to be attached to both JMenu and JPopupMenu objects,
will execute doWillBeVisible() just when the JMenu or JPopupMenu will become
visible. Both derived listeners, SaveMenuListener and EMSMenuListener implement
this call to first examine which object the menu is being called on (which
object is selected) and then examine whether the object has calls in it that
are relevant for saving or doing a cut/copy/paste. If so, these calls are
set properly within the menu. MainWindow attaches thse menu-listener to the
menu it creates in the top toolbar.