public class ListBoxCell : Cell
    {
        public override Type EditType
        {
            get
            {
                return typeof(ListBoxEditingControl);
            }
        }

        List<string> _items = new List<string>();

        public List<string> Items
        {
            get
            {
                return _items;
            }
        }

        protected override void InitializeEditingControl(int rowIndex, object formattedValue, CellStyle style)
        {
            // Apply the cell settings to editing control. 
            base.InitializeEditingControl(rowIndex, formattedValue, style);

            ListBoxEditingControl listBoxEditingControl = this.GcMultiRow.EditingControl as ListBoxEditingControl;

            for (int i = 0; i < this._items.Count; i++)
            {
                listBoxEditingControl.Items.Add(this._items[i]);
            }

            listBoxEditingControl.FormattedValue = formattedValue;
        }

        protected override void TerminateEditingControl(int rowIndex)
        {
            ListBoxEditingControl listBoxEditingControl = this.GcMultiRow.EditingControl as ListBoxEditingControl;
            
            // For performance reasons, MultiRow uses the same instance for all cells.
            // When leaving edit mode, clear items to prepare editing control for use next time.
            listBoxEditingControl.Items.Clear();

            base.TerminateEditingControl(rowIndex);
        }

        public override object Clone()
        {
            // When you derive from Cell and add new properties to the derived class, be sure to
            // override the Clone method to copy the new properties during cloning operations. 
            // You should also call the base class's Clone method so that the properties of the 
            // base class are copied to the new cell. 
            ListBoxCell listBoxCell = base.Clone() as ListBoxCell;

            listBoxCell.Items.AddRange(this.Items);

            return listBoxCell;
        }
    }