I have developped a component with a propriety of type List<BaseItem> where
BaseItem is a generic class. Two classes inherit from BaseItem : Noeud and
Item. Class Noeud has also a propriety of type List<BaseItem> so that we can
build a tree of BaseItem and assign it to the component. I have a custom
collection editor to edit the component's propriety (I gave up my first idea
to implement my own CollectionForm!).

I have a problem : there is a strange behavior when I want to add some
BaseItems to the second level of the tree. Let's take an example : if I
create an original tree like this : Noeud1(Noeud2,Item1), close all the
editor forms, and then, try to add an item in the collection of Noeud2,
nothing happens. But if I add a second item in Noeud1 first, and then create
an item in Noeid2, it works !

Can someone help me, please ?

Here my code :

#region Items

   public class BaseItem
   {
       private string _name;

       public string Name
       {
           get { return _name; }
           set { _name = value; }
       }
   }

   public class Noeud : BaseItem
   {
       private List<BaseItem> _items;

       [Editor(typeof(MyEditor), typeof(UITypeEditor))]
       
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
       public List<BaseItem> Items
       {
           get { return _items; }
           set { _items = value; }
       }

       public Noeud()
       {
           _items = new List<BaseItem>();
       }
   }

   public class Item : BaseItem
   {
       private string _misc;

       public string Misc
       {
           get { return _misc; }
           set { _misc = value; }
       }
   }
   #endregion

   #region Editor

   public class MyEditor : CollectionEditor
   {
       public MyEditor(Type type)
           : base(type)
       { }

       protected override Type[] CreateNewItemTypes()
       {
           return new Type[] { typeof(Noeud), typeof(Item) };
       }
   }
   #endregion

   #region Component

   public partial class MyComponent : Component
   {
       private List<BaseItem> _items;

       [Editor(typeof(MyEditor), typeof(UITypeEditor))]
       
[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
       public List<BaseItem> Items
       {
           get { return _items; }
           set { _items = value; }
       }

       public MyComponent()
       {
           InitializeComponent();
           _items = new List<BaseItem>();
       }

       public MyComponent(IContainer container)
       {
           _items = new List<BaseItem>();
           container.Add(this);

           InitializeComponent();
       }
   }
   #endregion