public virtual void Remove(PopupSelectColumn4Designer col)
 {
     foreach (object item in this.InnerList)
     {
         if ((PopupSelectColumn4Designer)item == col)
         {
             this.InnerList.Remove(item);
             break;
         }
     }
 }
 public virtual void Add(PopupSelectColumn4Designer col)
 {
     this.InnerList.Add(col);
 }