We're aware of this shortcoming in our diagram MVVM and we'll probably fix it (I say probably because the fix will be a breaking change and we still haven't decided on it), but for now you'll have to use the ConnectionManipulationConpleted event with something like this:
sender, ManipulationRoutedEventArgs e)
(e.ManipulationStatus == Telerik.Windows.Diagrams.Core.ManipulationStatus.Attaching)
var source = e.Connection.Source
var target = e.Shape
&& target !=
// BL here.
I hope I was able to help you and if you have further questions please feel free to ask.
TRY TELERIK'S NEWEST PRODUCT - EQATEC APPLICATION ANALYTICS for WPF.
Learn what features your users use (or don't use) in your application. Know your audience. Target it better. Develop wisely.
Sign up for Free application insights >>