Overview

A gadget is a type of element used for specialized tasks, such as input and output of text, presenting choices, and drawing graphical objects. This chapter takes a detailed look at fourteen of the fifteen gadgets specified for the MWAPI. (The final gadget type is introduced in this chapter, but due to its unique properties, the details of its characteristics are deferred to Chapter 6.) Although gadgets are a special type of window, they may not exist by themselves or be the parent to any entity.

The Gadget Types section describes each gadget type, points out some uses for the elements, and puts them into categories for ease of identification. A generic description for creating gadgets and their characterizing properties is found in the Creation and Modification and Gadget Attributes sections respectively. The attributes available for displaying a list of choices within a specified gadget are described in the Choice Attributes section. The Row and Column Attributes section discusses some of the unique characterizations available to one of the gadgets described in this chapter. The Event Processing section takes a look at event processing as it relates to gadgets. Demonstrations of sample applications, complete with code, build a platform for clear and concise discussions for the use of each gadget type in an application.

Gadgets are defined by the values assigned to their attribute nodes in the window SSVN. If not explicitly specified, some of these attributes receive default values from the MWAPI specification, the underlying windowing system, and...