Many options windows allow you to add an item to a list of available items. In the Extensions tab of the Workspace Registration options, for example, you can add an extension to the list of recognized extensions.
Add an item by right-clicking in the selection pane and choosing Add in the pop-up menu. The EA displays an empty text field next to a selected check box. Enter the name of the item in the text field and click outside the field.
Edit an item by selecting it and choosing Edit in the right-click menu. Delete an extension by selecting it and choosing Delete in the right-click menu.