private void Edit_Click(object sender, RoutedEventArgs e)
{
var item = MainTable.SelectedItem as Expnss;
OneItemChange ew = new OneItemChange(item);
ew.Show();
}
private void AddExp_Click(object sender, RoutedEventArgs e)
{
OneItemChange oneitem = new OneItemChange(new Expnss());
oneitem.ShowDialog();
}