Properties of Screen Elements

All components of a screen element are properties. When we talk about screen controls, these properties are classified into two groups: common properties and special properties. Common properties apply to many types of controls, and include:

size title value
color/intensity font     visible/invisible
enabled/disabled     ID  

Note that some common properties have a special meaning (or no meaning) for some control types. (A bar control, for example, wouldn't have a title, value, or font.)

Each control also has its own set of special properties. Special properties give a control a special attribute or capability. For example, an entry field can have the special properties Max-Text or Max-Lines, which determine how many characters or lines of information users will be permitted to enter in that field. All special properties require a value. Max-Text, for example, takes a numeric value that specifies the maximum number of characters that can be entered in the field. Some special properties are used by more than one control type. For example, the special properties that apply to bitmap buttons are also used by the push button, radio button, and check box controls.

Styles are a special type of property that affects the appearance or behavior of a control. For example, some of the styles that apply to a radio button include Bitmap, Framed, and Notify. Styles do not take a value. Most styles apply to only a certain type of control, although a few are common to all controls.

The process of setting control properties is discussed in Configuring Control Properties.