I forgot the attribute that will redirect the vs.net code generator to use a
public Property in a base class instead of a private field in the base
class. Does it ring a bell anybody?

Let me give you an example:

public class MyBaseForm : Form
{
   // With this XAttribute, when the derived form below is serialized in
the designer, the code generator will apply
   // any changes to this arraylist through the MyList property.
   // What is this XAttribute?
   [XAttribute("MyList")]
   private ArrayList someList;

   public ArrayList MyList
   {
       get{return this.someList;}
   }

   ...

}

In the derived class's InitializeComponent this the code that will be
inserted by the code generator:

public class MyDerivedForm : MyBaseForm
{
   ...

   private void InitializeComponent()
   {
       ...
       this.MyList.AddRange(new int[]{1});
   }
}

Thanks
-Praveen