Progress
Language Tutorial
for Windows
Working with Combo Boxes
A combo box consists of a fill-in field or variable, a button, and a selection list. A combo box can display any single value from the selection list in the fill-in field. This single value can also be assigned to the underlying field or variable.
Progress provides the following types of combo-box widgets:
- A SIMPLE combo-box widget with a read/write edit control and a selection list that is always visible. This widget is supported in graphical interfaces only, and only in Windows. If you specify a SIMPLE combo-box widget in a character interface, Progress treats it as a DROP-DOWN-LIST combo-box widget.
- A DROP-DOWN combo-box widget with a read/write edit control and a selection list that appears when you click the drop-down button. This option is supported in graphical interfaces only, and only in Windows. If you specify a DROP-DOWN combo-box widget in a character interface, Progress treats it as a DROP-DOWN-LIST combo-box widget.
- A DROP-DOWN-LIST combo-box widget with a read-only edit control and a selection list that appears when you click the drop-down button. This is the default.
You can use the combo-box widget with a CHARACTER, INTEGER, DECIMAL, LOGICAL, or DATE field or variable. The value representations in the drop-down list conform to the data type of the underlying field or variable. Like radio sets and selection lists, combo boxes are useful for representing fields or variables that have a limited number of possible values. One advantage of combo boxes is that they take up less screen space than radio sets and selection lists.
To select a value in the graphical interface, the end user can apply the following techniques:
- Position to the value in the drop-down list using the scroll bar and click on the value in the drop-down list using the SELECT mouse button.
- Enter text in the fill-in and allow the edit control to complete keyboard input to the combo-box, based on a potential or unique match, by searching through the items in the drop-down list.
- Position to the value in the drop-down list using the arrow keys and press SPACEBAR or RETURN to confirm the selection.
When the user selects an item, it triggers the VALUE-CHANGED event.
Thus, a combo box combines the functionality of a fill-in field, selection list, and radio set. It uses a fill-in field to display the selected item, and like a selection list displays a list of available values. Like a radio set, it supports sets of values for any Progress data type and allows selection of any one value at a time.
Figure 7–8 shows the parts of a combo box.
Figure 7–8: Parts of a Combo Box
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This is the syntax for defining a combo box.
Table 7–10 describes the combo box syntax elements.
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