The Visual Designer generates and maintains one class (.cls) file for each visual container that you design. This class contains the code needed to allow the ABL Virtual Machine (AVM) to display and enable the visual container. The code includes:
Progress Developer Studio for OpenEdge synchronizes the ABL code with the Visual Designer display, so that changes made in either editor are immediately reflected in the other. However, it is recommended that you use the Visual Designer tools for all changes to the UI, and edit only application logic (for example, event logic) in the ABL Editor. In this way you can reduce the chance of introducing errors in the UI code.