private void simpleButton1_Click(object sender, EventArgs e)
{
OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "All Excel|*.xls;*.xlsx";
if (dialog.ShowDialog() == DialogResult.OK)
{
tFileName.EditValue = dialog.FileName;
IEx = new ImportExcel(dialog.FileName);
List <string> sheets = IEx.GetSheets();
lSheet.Properties.Items.Clear();
lSheet.Properties.Items.AddRange(sheets.ToArray());
}
}