Fix: Exception when calling one of the context menu entries in XAML designer (like "Send to back", "Bring to front" etc.) on a root control. Example: The outermost Grid of a window.

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/Extensions/RightClickContextMenu.xaml.cs

@@ -46,6 +46,9 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 
 		void Click_BringToFront(object sender, RoutedEventArgs e)
 		{
+			if ((designItem.ParentProperty == null) || !designItem.ParentProperty.IsCollection)
+				return;
+			
 			var collection = this.designItem.ParentProperty.CollectionElements;
 			collection.Remove(this.designItem);
 			collection.Add(this.designItem);
@@ -53,6 +56,9 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 
 		void Click_SendToBack(object sender, RoutedEventArgs e)
 		{
+			if ((designItem.ParentProperty == null) || !designItem.ParentProperty.IsCollection)
+				return;
+			
 			var collection = this.designItem.ParentProperty.CollectionElements;
 			collection.Remove(this.designItem);
 			collection.Insert(0, this.designItem);
@@ -60,14 +66,20 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 		
 		void Click_Backward(object sender, RoutedEventArgs e)
 		{
+			if ((designItem.ParentProperty == null) || !designItem.ParentProperty.IsCollection)
+				return;
+			
 			var collection = this.designItem.ParentProperty.CollectionElements;
 			var idx = collection.IndexOf(this.designItem);
 			collection.RemoveAt(idx);
-			collection.Insert((--idx < 0 ? 0: idx), this.designItem);
+			collection.Insert((--idx < 0 ? 0 : idx), this.designItem);
 		}
 
 		void Click_Forward(object sender, RoutedEventArgs e)
 		{
+			if ((designItem.ParentProperty == null) || !designItem.ParentProperty.IsCollection)
+				return;
+			
 			var collection = this.designItem.ParentProperty.CollectionElements;
 			var idx = collection.IndexOf(this.designItem);
 			collection.RemoveAt(idx);