Fixes that sometimes both namespaces need to be compared.

This XAML works after this fix:

<Fluent:RibbonWindow RenderOptions.BitmapScalingMode="HighQuality"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:windows="clr-namespace:MCC.Visu.Configurator.Windows"
                    xmlns:Fluent="clr-namespace:Fluent;assembly=Fluent"
                    >
    <Grid>
            <Fluent:Ribbon >
                <Fluent:RibbonTabItem>
	 <Fluent:RibbonGroupBox>
                            <Fluent:Gallery>
                                <Fluent:Gallery.ItemContainerStyle>
                                    <Style />
                                </Fluent:Gallery.ItemContainerStyle>
                                <Image />
                            </Fluent:Gallery>
                 </Fluent:RibbonGroupBox>
                </Fluent:RibbonTabItem>
                </Fluent:Ribbon>
          </Grid>
</Fluent:RibbonWindow>

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

@@ -219,14 +219,14 @@ namespace ICSharpCode.WpfDesign.XamlDom
 			return new XamlObject(this, xml, elementType, instance);
 		}
 		
-		internal string GetNamespaceFor(Type type)
+		internal string GetNamespaceFor(Type type, bool getClrNamespace = false)
 		{
 			if (type == typeof (DesignTimeProperties))
 				return XamlConstants.DesignTimeNamespace;
 			if (type == typeof (MarkupCompatibilityProperties))
 				return XamlConstants.MarkupCompatibilityNamespace;
 
-			return _typeFinder.GetXmlNamespaceFor(type.Assembly, type.Namespace);
+			return _typeFinder.GetXmlNamespaceFor(type.Assembly, type.Namespace, getClrNamespace);
 		}
 
 		internal string GetPrefixForNamespace(string @namespace)

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

@@ -317,10 +317,11 @@ namespace ICSharpCode.WpfDesign.XamlDom
 		{
 			var localName = elementType.Name + "." + propertyName;
 			var namespaceURI = xamlDocument.GetNamespaceFor(elementType);
+			var clrNamespaceURI = xamlDocument.GetNamespaceFor(elementType, true);
 
 			foreach (XmlNode childNode in node.ChildNodes)
 			{
-				if (childNode.LocalName == localName && childNode.NamespaceURI == namespaceURI)
+				if (childNode.LocalName == localName && (childNode.NamespaceURI == namespaceURI || childNode.NamespaceURI == clrNamespaceURI))
 				{
 					return childNode;
 				}

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

@@ -117,11 +117,11 @@ namespace ICSharpCode.WpfDesign.XamlDom
 		/// <summary>
 		/// Gets the XML namespace that can be used for the specified assembly/namespace combination.
 		/// </summary>
-		public string GetXmlNamespaceFor(Assembly assembly, string @namespace)
+		public string GetXmlNamespaceFor(Assembly assembly, string @namespace, bool getClrNamespace = false)
 		{
 			AssemblyNamespaceMapping mapping = new AssemblyNamespaceMapping(assembly, @namespace);
 			string xmlNamespace;
-			if (reverseDict.TryGetValue(mapping, out xmlNamespace)) {
+			if (!getClrNamespace && reverseDict.TryGetValue(mapping, out xmlNamespace)) {
 				return xmlNamespace;
 			} else {
 				return "clr-namespace:" + mapping.Namespace + ";assembly=" + mapping.Assembly.GetName().Name;