Cancel from DialogPropertyEditor causes Element already has a logical parent. It must be detached from the old parent before it is attached to a new one.

Question

Hello, I've created a DialogPropertyValueEditor that I've attached to a Items collection property. This editor works fine, I can add, insert, delete and move items in the collection. The problem occurs when user Cancels the dialog. In this case, I get:

Element already has a logical parent. It must be detached from the old parent before it is attached to a new one. at MS.Internal.DocumentTreeManagers.ItemUpdater.ApplyDelta(INodeHost nodeHost, DeltaItemCollection delta, ModifiableDocumentTree root, DocumentNodeDictionary oldTable, Boolean updateTable, DocumentNodeDictionary deletedItems, Comparison`1 compare) at Microsoft.Windows.Design.Documents.Trees.DocumentTreeManager.ApplyDelta(Delta delta, Comparison`1 compare) at Microsoft.Windows.Design.Documents.Trees.ModelDocumentTreeManager.ApplyEditingScopeDelta(Delta delta, Boolean resetDamage) at Microsoft.Windows.Design.Documents.Trees.ModelDocumentTreeManager.OnEditingScopeAborted(ModelEditingScopeImpl scope) at Microsoft.Windows.Design.Documents.Trees.ModelDocumentTreeManager.ModelEditingScopeImpl.OnRevert(Boolean finalizing) at Microsoft.Windows.Design.Model.ModelEditingScope.Revert()

I assume this occurs because I have modified items in the collection by removing and re-adding them, and then the Revert encounters a remove and tries to re-add the item. If I don't remove and re-add items in the collection, then the changes aren't propagated to the XAML.

Let me know if you need more info. Thanks, Jane

Answer 1

I think I figured it out.  When an item changes I was doing a remove and insert.   I need to do an insert and remove, so that the Revert when Cancel is called, it does not think I'm adding an item that already exists.  In addition, I had to make a copy of my object for insert.

Answer 2

Hello, Jane

You question is about WPF designer, and this forum is about visual studio extensibility or visual studio SDK related. So I moved your thread to WPF Designer forum.

Thanks

Chao