Arithmetic in Generic Classes in C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel.Design;

namespace RichTextBoxDAL {

    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
    public class RichTextBoxDesigner : System.Windows.Forms.Design.ControlDesigner {

        private DesignerActionListCollection fActionLists;


        public override DesignerActionListCollection ActionLists {
            get {
                if (null == fActionLists) {
                    fActionLists = new DesignerActionListCollection();
                    fActionLists.Add(
                        new RTBDAL(this.Component));
                }
                return fActionLists;
            }
        }

    }
}