FarPoint.Win.Spread.CellType.ListBoxCellType listcell = new FarPoint.Win.Spread.CellType.ListBoxCellType();
listcell.SelectionMode = SelectionMode.MultiSimple;
listcell.ItemData = new string[] { "One", "Two", "Three"};
listcell.Items = new string[] { "One", "Two", "Three"};
fpSpread1.Sheets[0].Cells[0, 0].CellType = listcell;