Reflector says StringCollectionEditor is an internal class.
internal class StringCollectionEditor : CollectionEditor
You may have to implement your own.
Note ListBox.Items uses:
[ Editor("System.Windows.Forms.Design.ListControlStringCollectionEditor,
System.Design, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b03f5f7f11d50a3a", typeof(UITypeEditor)) ]
public ListBox.ObjectCollection Items
{
}
ListControlStringCollectionEditor derives from CollectionEditor.
I don't know why this class (CollectionEditor) is not public, doesn't make
any sense to me.

Signature
Francisco Padron
www.chartfx.com
>I am creating a custom control which have an "AutoCompleteStringCollection"
>property, which is like in TextBox control. How I can tell the designer I
>wan to lauch String Collection Editor.