Maybe I found a Solution. But with a problem.
I add an Event to the CollectionViewSource of the Combobox:
CollectionViewSource.GetDefaultView(Recipes).CurrentChanging += RecipeViewCurrentChanging;
In theRecipeViewCurrentChanging i wan't to cancel the event. The problem is that the Event of the ActiveItem Property comes before the RecipeViewCurrentChanging event. :-(
How can I cancel ActiveItem PropertyChanged Event ?