Every menu option you add to a menu has a Skip For check box on its Prompt Options dialog through which you can enter a logical expression to disable or enable the option. If the logical expression evaluates to true (.T.), Visual FoxPro disables the option.
When you build an application, you must determine when, if ever, a menu option should be disabled. Then, you enter a logical expression into the option’s Skip For to disable the option when the disabling condition applies.
See the “Disabling Menu Options” section in the Menus chapter of the Technical Reference manual for suggestions on when and how to disable menu options.