Progress
Programming
Handbook
Working with Combo Boxes
In general, it is important to keep in mind that a combo box maintains three types of data:
- The drop-down list, which is the available set of input values in character string form
- The screen buffer value displayed in the fill-in, which is the currently selected character string from the drop-down list
- The record buffer value, which is the current value of the underlying field or variable stored according to the field or variable data type
For an end user, it is only possible to select a value for the combo box from the available drop-down list. As with any data-representation widget, the application must assign the combo box with the ASSIGN statement to move this value into the record buffer.
It is possible for the application to assign any value to the underlying field or variable consistent with its data type. However, the application can only display a value from the field or variable (move the record buffer value to the screen buffer) that is also available in the combo box drop-down list.
NOTE: If you set an initial value for the underlying field or variable (through assignment or the INITIAL option), you must explicitly display as well as enable the combo box widget in order to move the initial value to the screen buffer for display in the fill-in. Otherwise when you enable the widget, nothing is displayed.
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