A single menu strip may be attached to multiple windows in an application
by calling SetMenuStrip() for each window.  All of the windows must be on
the same screen for this to work.  Since menus are always associated with
the active window on a given screen, and since only one window may be
active on a screen at a time, only one window may display the shared menu
strip at any given time.

When multiple windows share a single menu strip, they will all "see" the
same state of the menus, that is, changes made to the menu strip from one
window will still exist when a new window is activated.  If the
application wishes to share menu strips but to have a different flag and
enabled status for each window, the program may watch IDCMP_ACTIVEWINDOW
for the windows and modify the menu strip to match the active window's
requirements at that point.  In addition, the application must also set
IDCMP_MENUVERIFY to insure that the user can't access the menus of a newly
activated window before the application can process the IDCMP_ACTIVEWINDOW
message.

ResetMenuStrip() may also be used to set the menus for the multiple
windows as long as SetMenuStrip() is used first to attach the menu strip
to any one window and no major changes are made to the menu strip before
the calls to ResetMenuStrip() on subsequent windows.