To create a tab or activity in your app editor, create a class derived from EditorActivityViewModelBase. This class lets you override the following methods and properties:

1. Label: This sets the name of the tab that will appear at the top of the app editor.
2. RegisterCommands: This registers a command for the tab.
3. OnDeactivated: This is set when the tab is deactivated.
4. OnActivated: This is set when the tab activated.
5. OnInitialized: This is set when the tab is initialized.

EditorActivityViewModelBase has the following public methods that you can use to implement new app editor activity:

1. SetDirty: Enables a user to save changes to the configuration in the editor.
2. IsActive: In an editor with multiple tabs, this method indicates whether a tab is active or inactive.
3. IsReadOnly: This method indicates if the editor was opened in read-only mode.

EditorActivityViewModelBase contains the following protected methods/properties that can used when implementing new app editor activity:

1. CommandManager: Register and unregister commands.
2. Editor: IEditor implemented by framework.