Fixed bug; Only sets the inner text of an XML element if the element type defines a Content property.

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

@@ -169,9 +169,12 @@ namespace ICSharpCode.WpfDesign.XamlDom
 			
 			XmlElement xml = _xmlDoc.CreateElement(elementType.Name, GetNamespaceFor(elementType));
 			
-			if (hasStringConverter) {
+			if (hasStringConverter &&
+			    XamlObject.GetContentPropertyName(elementType) != null)
+			{
 				xml.InnerText = c.ConvertToInvariantString(instance);
 			}
+
 			return new XamlObject(this, xml, elementType, instance);
 		}
 		

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

@@ -32,10 +32,7 @@ namespace ICSharpCode.WpfDesign.XamlDom
 			this.elementType = elementType;
 			this.instance = instance;
 
-			var contentAttrs = elementType.GetCustomAttributes(typeof(ContentPropertyAttribute), true) as ContentPropertyAttribute[];
-			if (contentAttrs != null && contentAttrs.Length > 0) {
-				this.contentPropertyName = contentAttrs[0].Name;
-			}
+			this.contentPropertyName = GetContentPropertyName(elementType);
 
 			ServiceProvider = new XamlObjectServiceProvider(this);
 			CreateWrapper();
@@ -130,6 +127,21 @@ namespace ICSharpCode.WpfDesign.XamlDom
 			return newElement;
 		}
 		
+		/// <summary>
+		/// Gets the name of the content property for the specified element type, or null if not available.
+		/// </summary>
+		/// <param name="elementType">The element type to get the content property name for.</param>
+		/// <returns>The name of the content property for the specified element type, or null if not available.</returns>
+		internal static string GetContentPropertyName(Type elementType)
+		{
+			var contentAttrs = elementType.GetCustomAttributes(typeof(ContentPropertyAttribute), true) as ContentPropertyAttribute[];
+			if (contentAttrs != null && contentAttrs.Length > 0) {
+				return contentAttrs[0].Name;
+			}
+			
+			return null;
+		}
+		
 		internal override void AddNodeTo(XamlProperty property)
 		{	
 			if (!UpdateXmlAttribute(true)) {