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If you do not register a TimelineSourceInterface you will not be able to provide enable/disable options to users but you can still generate Timeline activity with TimelineStartActivity.

Custom Property Pages

To display a custom property page for your activity type register a UI-side source with TimelineUIRegisterSource, providing a TimelineUISourceInterface that the framework will use to retrieve a property page to place into the Timeline property sheet.

Context Menu Actions

Items in the Timeline can be right-clicked to display a menu of actions that can be performed on that item. To add your own actions, register a type handler in the UI with TimelineUIRegisterTypeHandler and provide a ActivityTypeHandlerInterface that the framework will use to access the actions that you provide.