some improvements

Pilz.Plugins.Advanced.UI.Telerik/Extensions.cs

@@ -63,7 +63,7 @@ public static class Extensions
     /// You usually don't set customClickHandler if you set this parameter to <see cref="true"/>.</param>
     /// <param name="customClickHandler">Adds a custom click handler. If addDefaultHandler is true, it will only work on <see cref="PluginFeature"/>s.<br/>
     /// You usually don't set addDefaultHandler to true if you set this parameter to something not null.</param>
-    public static void InsertItemsTo(this IEnumerable<PluginFeature> features,
+    public static IEnumerable<RadMenuItem> InsertItemsTo(this IEnumerable<PluginFeature> features,
         RadItemOwnerCollection itemsCollection,
         bool addDefaultHandler = false,
         EventHandler? customClickHandler = null,
@@ -76,6 +76,7 @@ public static class Extensions
         var insertDefault = customDefault ?? (insertMode.HasFlag(FeatureInsertMode.DefaultStart) ? 0 : itemsCollection.Count);
         var insertTop = customTop ?? (insertMode.HasFlag(FeatureInsertMode.InsertTop) || insertMode.HasFlag(FeatureInsertMode.DefaultStart) ? 0 : insertDefault);
         var insertBottom = customBottom ?? (insertMode.HasFlag(FeatureInsertMode.InsertBottom) || insertMode.HasFlag(FeatureInsertMode.DefaultEnd) ? itemsCollection.Count : insertDefault);
+        var insertedItems = new List<RadMenuItem>();
 
         foreach (var feature in features)
         {
@@ -112,7 +113,12 @@ public static class Extensions
                     itemsCollection.Insert(insertBottom++, item);
                     break;
             }
+
+            if (item.Parent != null)
+                insertedItems.Add(item);
         }
+
+        return insertedItems;
     }
 
     private static void RadMenuItem_RMMethod_Click(object? sender, EventArgs e)