FarPoint.Web.Spread.DateTimeCellType dt = new FarPoint.Web.Spread.DateTimeCellType();
System.Globalization.DateTimeFormatInfo dtf = new System.Globalization.DateTimeFormatInfo();
dtf.LongDatePattern = "D";
dtf.ShortDatePattern = "M/d/yyyy";
dt.DateTimeFormat = dtf;
dt.MaximumValue = new System.DateTime(2020, 12, 31);
dt.MinimumValue = new System.DateTime(1950, 1, 1);
dt.DropDownControlStyleInfo.BackColor = Color.Beige;
dt.ShowPopupButton = true;
FpSpread1.ActiveSheetView.Cells[0, 0].CellType = dt;
FpSpread1.ActiveSheetView.Cells[0, 0].Value = DateTime.Now;