Event functions are written to provide special capabilities to the end user. These functions can be tailored specifically to the circumstances of an individual form. Event functions can be made available at different times. An event function could be available at any time in your application, or only when the user is processing a particular form, or only when the user is in a particular field or type of field (such as a memo field).
Event functions are typically attached to a key (or a key combination on terminals) and are called when the user presses that key. However, there are other ways to use event functions also. See Chapter 38, "Writing Event Functions," and Chapter 39, "Installing Event Functions and Modifying Event Tables," for more information on writing and installing event functions.
Vermont Views uses event functions extensively, for performing such tasks as pulling up a choice list and displaying help information. Some other examples of uses for event functions are: to move to a specific item on the form, to move to a specific field on a scrollable region, to increment or decrement the value in a field, to do a certain task (search in a database, for instance), make an intermediate save of the data entered in the form (using fm_convert()), blank out a row in a scrollable region, or insert a blank data row in a scrollable region.
What You Should Not Do in Event Functions
Writing and Installing Event Functions
