string f;
f = "c:\\zipfile\\test1.xlsx";
// Open an existing file named test1.xlsx
System.IO.FileStream s = new System.IO.FileStream(f, System.IO.FileMode.Open, System.IO.FileAccess.ReadWrite);
gcSpreadSheet1.OpenExcel(s);
//gcSpreadSheet1.OpenExcel(s, GrapeCity.Windows.SpreadSheet.Data.ExcelOpenFlags.RowAndColumnHeaders);
//gcSpreadSheet1.OpenExcel(s, "12Test9");
//gcSpreadSheet1.OpenExcel(s, GrapeCity.Windows.SpreadSheet.Data.ExcelOpenFlags.RowAndColumnHeaders, "12Test9");
s.Close();
gcSpreadSheet1.Invalidate();