Once you’ve connected your add-in, you’ll likely want to expose it in the IDE. Of course, add-ins don’t necessarily have to be initiated from the IDE or even have a visible user interface. You can activate them behind the scenes through events and they can work unnoticed in the background. Most add-ins, however, are activated through either a menu command or toolbar button.
You must decide how the add-in will be initiated — by a menu command, a toolbar button, or by the occurrence of an event. Since chances are good that most add-ins you create will be visible in the development environment, you’ll want to be able to control when they’re active and when they’re not.
There are five ways to control an add-in’s operation: