Bugfix: Copyied XAML contains d1p1 as Namespace Prefix for Added Name Attribute

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.XamlDom/Project/XamlObject.cs

@@ -514,8 +514,18 @@ namespace ICSharpCode.WpfDesign.XamlDom
 
 			if (value == null)
 				element.RemoveAttribute(name, XamlConstants.XamlNamespace);
+			else
+			{
+				var prefix = element.GetPrefixOfNamespace(XamlConstants.XamlNamespace);
+				if (!string.IsNullOrEmpty(prefix))
+				{
+					var attribute = element.OwnerDocument.CreateAttribute(prefix, name, XamlConstants.XamlNamespace);
+					attribute.InnerText = value;
+					element.SetAttributeNode(attribute);
+				}
 				else
 					element.SetAttribute(name, XamlConstants.XamlNamespace, value);
+			}
 			
 			if (isNameChange) {
 				bool nameChangedAlreadyRaised = false;