Updated MenuItemCollection with MenuItemList for full featured List access to the items. Added the MenuRendering event to TreeController, updated the tree controller events to be TypedEventHandler's though developers will need to cast the TreeController to the type they are expecting - still better than 'object'.

src/Umbraco.Web.UI/App_Plugins/MyPackage/Trees/LegacyTestTree.cs

@@ -33,7 +33,7 @@ namespace Umbraco.Web.UI.App_Plugins.MyPackage.Trees
         protected override MenuItemCollection GetMenuForNode(string id, FormDataCollection queryStrings)
         {
             var menu = new MenuItemCollection();
-            menu.AddMenuItem(new MenuItem("create", "Create"));
+            menu.Add(new MenuItem("create", "Create"));
             return menu;
         }
     }