Texas Instruments TI89 Developer Guide - Page 129

Chapter 9: Application Control Flow 87 9.6.2. The application should be compiled with the address of its menu in its OO_APP_DEFAULT_MENU frame attribute. When an application receives a CM_ACTIVATE message, default event handling checks the application's OO_APP_DEFAULT_MENU attribute. If it finds a pointer to a menu there, it calls MenuBegin to draw the menu across the top of the calculator screen, and saves a handle to the menu in application frame attribute OO_APP_DEFAULT_MENU_HANDLE. Default event handling of CM_DEACTIVATE calls MenuEnd on the application's current menu and frees the menu handle. Dynamic Menus An application may need to change menu contents based on its current state. In this case, the application needs to take a more active role in building menus, managing menu memory, and setting up the user interface. Creating a new menu - an application uses MenuNew and MenuAddText to create dynamic menus. The application then calls SetAppDefaultMenuHandle to place the new menu's handle in the application's frame where default event handling can find it for function-key processing. Disposing of a menu - an application disposes of a menu by calling MenuEnd to release its memory resources and SetAppDefaultMenuHandle(MY_APP_ID(MyAppObj), H_NULL) to unregister the menu with the default event handler. The application must be able to display a dynamic menu when the application is activated and change menus while the application is active. Default event handling automatically releases menu resources when the application is deactivated. An application is activated when it receives the CM_ACTIVATE message from the OS. The application should respond to this message by creating a new menu as described above. An application changes menus by disposing of the current menu and creating a new menu. Default handling of the CM_DEACTIVATE event automatically frees the application's menu handle and sets attribute OO_APP_DEFAULT_MENU_HANDLE to H_NULL. TI-89 / TI-92 Plus Developer Guide Not for Distribution Beta Version January 26, 2001