when I drag and drop from a Palette OnNodeAdded is called two times. How can I validate if it is an “enter-diagram”-OnNodeAdded-call or a “dropped-on-diagram”-OnNodeAdded-call?

i solved my problem. The first call (“enter-diagram”-OnNodeAdded-call) causes a OnNodeRemoved, the second not.

Also, the parts that are created upon a drag-enter are temporary ones. You can check the value of Diagram.SelectedParts.First().Layer.IsTemporary. (I hope I typed that correctly.)

Thanks a lot, i searched for such a property.