IDCMP_MENUVERIFY gives the program the opportunity to react before menu
operations take place and, optionally, to cancel menu operations. Menus
may be completely disabled by removing the menu strip with a call to
ClearMenuStrip().

 A Warning on the MENUSTATE Flag    Shortcuts and IDCMP_MENUVERIFY 
 Menu Verify                        IDCMP_MENUVERIFY and Deadlock