To add a new part to an application, do the following:
Notice that the class names shown in the drop-down list change whenever you select a different part type. For visual and nonvisual parts, you likely want the defaults. For Smalltalk classes, select from the list the Smalltalk class whose attributes and methods are of most use to your part.
If you do not see the class from which the part will inherit in the list, type the name of the superclass in the text pane.