Based on discussion https://wpftoolkit.codeplex.com/discussions/641833.
Using the NewItemTypes attribute is not taken into account in the collectionControl of the PropertyGrid since v2.3.
Comments: ** Comment from web user: CocacolaCompany **
Using the NewItemTypes attribute is not taken into account in the collectionControl of the PropertyGrid since v2.3.
Comments: ** Comment from web user: CocacolaCompany **
When are you going to release/fix this bug in community edition?
Thanks