Before testing your ToDoList application, you should save the work you have done.
In VisualAge, the current state of the system is stored in an image file, called ABT.ICX. When you save your image, you are saving the current state of all the applications and parts you have created and the state of any windows that you currently have open. When you restart VisualAge, the system will be restored to the state it was in when you last saved your image. You should periodically save your image while developing your applications and save your image prior to exiting VisualAge.
You can also save any changes you have made to a part. When you save changes to a part, you are replacing the old specification of the part with a new one. When you do this, VisualAge will be using the new specification of the part for all new uses of it. You should save your changes to a part periodically as you are working with it and when you have finished editing it.