How to wait for all storyboards on a control to finish?

I have created a custom control which has a style defined for it in themes/generic.xaml. The co开发者_StackOverflow中文版ntrol defines some additional RoutedEvents. For these events the style, or any style that overrides it, could define EventTriggers that start a storyboard.

When i raise a RoutedEvent from my control, how can i wait for all of these storyboards to finish? In my control logic i do not know if and which storyboards have triggered, i'd like to keep it that way. I'm looking for a general way to wait for all storyboards that are currently playing for a specific element.