About List Box
The PTC Mathcad Prime List Box control enables you to accept the user input as a selection from a list. The default output is the number of the item selected in the list. It can be converted to the selected label or other data type in the script using the List Box class. You can change the appearance of a list box by right-clicking and choosing > or access its properties through the script.
There are four events in this default script for List Box: Start, Exec, Stop, SelChanged.The list box is initialized and populated in the Start event. In general, the Start event can be used to further modify the appearance of the list box or its elements. It is recommended to set the properties and the list at the start event. You can also format the list box using the Properties tab. The Exec event is where inputs and outputs can be processed, including the conversion of the selection from the default integer output to other numerical or string outputs. The list can be updated in the Exec event.The SelChanged event is generally used to re-execute the control after the user has changed their selection; however, this event might trigger other actions, such as alerts or script-based calculations.