How to create custom controls containing populated lists?

How to properly create cus开发者_开发百科tom controls containing populated lists?

For example: I need a combobox control which contains a list of products, then I would reuse this control in other project.

My code is this:

Public Class ProductCombo
    Inherits ComboBox
    Public Sub New()
        Me.Items.Add("Product 1")
        Me.Items.Add("Product 2")
    End Sub
End Class

and it works but when I run the project each item is duplicated - this is because list is populated twice. First when user add a control to form, second by designer when project is started.

I already found a solution to prevent adding items in edit mode, but this is not what I need. I would like to have them existing in edit mode so they could be edited at this point.

Is there a solution to this problem?

  protected override void OnCreateControl()
  {
     base.OnCreateControl();
     if (Items.Count == 0)
     {
        Items.Add("Product 1");
        Items.Add("Product 2");
     }
  }