private void button_Click(object sender, RoutedEventArgs e)
{
AddPeriod addPeriod = new AddPeriod();
addPeriod.mode = 1;
addPeriod.Show();
}
private void edit_Click(object sender, RoutedEventArgs e)
{
var x = ((Period)datagridview.SelectedItem);
AddPeriod addPeriod = new AddPeriod();
addPeriod.periodid = x.PeriodID;
addPeriod.mode = 2;
addPeriod.Show();
}