Specifications

2 Creating a GUI
2-14
Callback Properties
Components use callbacks to do their work. A callback is a function that
executes when a user performs a specific action such as clicking a push button,
selecting a menu item, or pressing a keyboard key, or when a component is
created or deleted. Each component and menu item has properties that specify
its callbacks. When you create a GUI, you must program the callbacks you need
to control operation of the GUI.
A component can have many callback properties, but the most common one is
the
Callback property. The code you provide for the Callback property
performs the primary work of the component. It executes, for example, when a
user presses a push button, moves a slider, or selects a menu item.
“Programming the GUI” on page 2-17 shows you how to program the
Callback
property for the push buttons and pop-up menu in this example.
The Tag Property
The Tag property provides a string as a unique identifier for each component.
GUIDE uses this identifier to construct unique callback names for the different
components in the GUI.