HP 3000 Manuals HP 3000 Manuals
Chapter 6 Screen Development HP ALLBASE/4GL Screens This chapter describes the HP ALLBASE/4GL screen processing logic. It also describes the screens in the screen development menu and the screen painter. HP ALLBASE/4GL supports three types of screens. They are menus, data screens, and windows. Menus HP ALLBASE/4GL menus present the user with a choice of options within the application. When the user chooses an option from a menu, HP ALLBASE/4GL executes the selected option. The following actions can be executed as a result of user selections from a menu: * Another menu * Data screen. * Help screen. * Function. * Process. * Background process. * Report. * External program. When HP ALLBASE/4GL displays a menu, any current process, function, decision table, report, or data screen is terminated immediately. Data Screens HP ALLBASE/4GL data screens allow the user to enter data for the application and also allow the application to display information for the user. Data screens consist of input fields, display fields, and literals or titles. Data screens can also have a scroll area for information display. HP ALLBASE/4GL can overlay a window on a data screen. The window, which must be defined as a screen in itself, can contain data entry and display fields. Windows A window is a screen image that HP ALLBASE/4GL overlays on an existing screen to allow display or entry of additional data. HP ALLBASE/4GL can display a number of successive windows on the same screen. System Items All HP ALLBASE/4GL screens can contain system items. These are fields that display the contents of certain system or user defined fields. System items can display: * The current date. * Communication area fields. * Master titles. * Application titles. * Numeric or alphanumeric constants. * Variables or calculated items. * Scratch-pad fields. Function Keys All HP ALLBASE/4GL screens can have one or more sets of function keys. These function keys allow the user to select various options or system functions.